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Predictors of Postconcussive Symptoms 3 Months After Mild Traumatic
Brain Injury
Jennie Ponsford
Monash University; Monash-Epworth Rehabilitation Research
Centre, Epworth Hospital; and National Trauma Research
Institute, Melbourne, Australia
Peter Cameron and Mark Fitzgerald
Monash University; Alfred Hospital; and National Trauma
Research Institute, Melbourne, Australia
Michele Grant
Monash University; Monash-Epworth Rehabilitation Research
Centre, Epworth Hospital; and National Trauma Research
Institute, Melbourne, Australia
Antonina Mikocka-Walus
Monash University, National Trauma Research Institute and
University of South Australia
Michael Schönberger
Monash University; Monash-Epworth Rehabilitation Research Centre, Epworth Hospital; and University of Freiburg
Objective: There is continuing controversy regarding predictors of poor outcome following mild
traumatic brain injury (mTBI). This study aimed to prospectively examine the influence of preinjury
factors, injury-related factors, and postinjury factors on outcome following mTBI. Method: Participants
were 123 patients with mTBI and 100 trauma patient controls recruited and assessed in the emergency
department and followed up 1 week and 3 months postinjury. Outcome was measured in terms of
reported postconcussional symptoms. Measures included the ImPACT Post-Concussional Symptom
Scale and cognitive concussion battery, including Attention, Verbal and Visual memory, Processing
Speed and Reaction Time modules, pre- and postinjury SF-36 and MINI Psychiatric status ratings, VAS
Pain Inventory, Hospital Anxiety and Depression Scale, PTSD Checklist–Specific, and Revised Social
Readjustment Scale. Results: Presence of mTBI predicted postconcussional symptoms 1 week postin-
jury, along with being female and premorbid psychiatric history, with elevated HADS anxiety a
concurrent indicator. However, at 3 months, preinjury physical or psychiatric problems but not mTBI
most strongly predicted continuing symptoms, with concurrent indicators including HADS anxiety,
PTSD symptoms, other life stressors and pain. HADS anxiety and age predicted 3-month PCS in the
mTBI group, whereas PTSD symptoms and other life stressors were most significant for the controls.
Cognitive measures were not predictive of PCS at 1 week or 3 months. Conclusions: Given the evident
influence of both premorbid and concurrent psychiatric problems, especially anxiety, on postinjury
symptoms, managing the anxiety response in vulnerable individuals with mTBI may be important to
minimize ongoing sequelae.
Keywords: traumatic brain injury, concussion, outcome assessment
Mild traumatic brain injury (mTBI) is a prevalent neurological
condition, affecting 100 –300 out of 100,000 annually (Cassidy et
al., 2004; Hirtz et al., 2007). Although studies have shown that
most cases make a full recovery within 3 months of injury,
approximately 15%–25% of cases experience ongoing symptoms,
which may cause significant disability (Carroll et al., 2004; Pons-
ford et al., 2000), with frequencies varying according to population
studied, setting, and timing of recruitment (Belanger, Curtiss,
Demery, Lebowitz, & Vanderploeg, 2005). The term postconcus-
sion syndrome (PCS) refers to the somatic, cognitive, emotional,
motor, or sensory symptoms ascribed to a concussion or head
injury (Benton, 1989). These symptoms commonly include head-
This article was published Online First April 2, 2012.
Jennie Ponsford and Michele Grant, Monash University, Monash-
Epworth Rehabilitation Research Centre, Epworth Hospital, and National
Trauma Research Institute, Melbourne, Australia; Peter Cameron, Monash
University, Alfred Hospital, and National Trauma Research Institute, Mel-
bourne, Australia; Mark Fitzgerald, Monash University, Alfred Hospital,
and National Trauma Research Institute, Melbourne, Australia; Antonina
Mikocka-Walus, Monash University, School of Nursing and Midwifery,
University of South Australia, National Trauma Research Institute, Mel-
bourne, Australia; and Michael Schönberger, Monash University, Monash-
Epworth Rehabilitation Research Centre, Epworth Hospital, and Depart-
ment of Rehabilitation Psychology, Institute of Psychology, University of
Freiburg, Germany.
This research was funded by a grant from the Victorian Neurotrauma
Initiative. The authors also gratefully acknowledge the assistance of staff in
the Alfred Hospital Emergency and Trauma Care Department.
Correspondence concerning this article should be addressed to Pro-
fessor Jennie Ponsford, School of Psychology and Psychiatry, Monash
University, Clayton, Victoria 3800, Australia. E-mail: jennie.ponsford@
monash.edu
Neuropsychology © 2012 American Psychological Association
2012, Vol. 26, No. 3, 304–313 0894-4105/12/$12.00 DOI: 10.1037/a0027888
304
aches, dizziness, visual disturbance, memory difficulties, poor
concentration, mental slowness, difficulty dividing attention, alco-
hol intolerance, fatigue, irritability, depression, and anxiety (Car-
roll et al., 2004; Kraus et al., 2005; Lundin, de Boussard, Edman,
& Borg, 2006; Ponsford et al., 2000; Yang, Tu, Hua, & Huang,
2007). Given the high frequency of mTBI, it is neither realistic nor
necessary to provide comprehensive treatment to all people with
these injuries. However, single-session therapies applied to at-risk
individuals with mTBI may be efficacious (Mittenberg, Canyock,
Condit, & Patton, 2001). Currently, clinicians assessing these
patients do not have clear guidelines as to how to predict who is
likely to experience ongoing symptoms. The early identification of
such cases might allow for the early provision of management
strategies to circumvent ongoing problems. Understanding the
causes of ongoing PCS may also guide treatment.
Although numerous injury-related factors have been associated
with continuing symptoms following mTBI, findings have been
inconsistent (Carroll et al., 2004). The strongest predictors of
outcome in moderate to severe TBI—namely, duration of loss of
consciousness, initial Glasgow Coma Scores (GCS), and duration
of posttraumatic amnesia (PTA), which are measures of injury
severity— have not been shown to be significant predictors of
ongoing sequelae following mTBI (Carroll et al., 2004; Ponsford
et al., 2000). The reasons for this are unclear, but measurement
issues may contribute to this (Ponsford et al., 2004). Although
presence of intracranial abnormalities has been associated with
poorer cognitive performance or persistent PCS in some studies
(Lange, Iverson, & Franzen, 2009; Lewine et al., 2007; Lo,
Shifteh, Gold, Bello, & Lipton, 2009; Sadowski-Cron et al., 2006;
Williams, Levin, & Eisenberg, 1990), patients with uncomplicated
mTBI do not show intracranial abnormalities. Poorer performances
on cognitive tests of reaction time (RT), processing speed, imme-
diate memory, verbal memory, and visual memory have also been
documented in mTBI patients in relation to trauma controls early
after injury (Landre, Poppe, Davis, Schmaus, & Hobbs, 2006;
Peterson, Stull, Collins, & Wang, 2009; Ponsford et al., 2000;
Sheedy, Geffen, Donnelly, & Faux, 2006; Shores et al., 2008),
although there have been mixed findings regarding the relationship
of cognitive impairments with PCS (Landre et al., 2006; Meares et
al., 2008; Ponsford et al., 2000).
Of possible demographic predictors, female gender has been
associated with greater reporting of PCS (Dischinger, Ryb, Kufera,
& Auman, 2009; Meares et al., 2008; Ponsford et al., 2000). Age
over 40 years was a negative prognostic factor in one study
(Thornhill et al., 2000), but not other studies of mTBI, despite
being a strong predictor of poorer outcome following moderate to
severe TBI (Hukkelhoven et al., 2003). One study (Stulemeijer,
Vos, Bleijenberg, & van der Werf, 2007) found that lower educa-
tion predicted cognitive complaints 6 months postinjury. Findings
regarding the effects of multiple concussive head injuries have
been mixed. Results of a recent meta-analysis suggested that
multiple self-reported concussions were associated with poorer
performances on tests of delayed memory and executive function
(Belanger, Spiegel, & Vanderploeg, 2010). However, the clinical
significance of these differences was unclear.
The presence of preinjury psychiatric or other health problems
and other life stressors have emerged as significant predictors of
poorer mTBI outcomes in several studies (Carroll et al., 2004;
Kashluba, Paniak, & Casey, 2008; McLean et al., 2009; Meares et
al., 2008; Ruff, 2005; Wood, 2004). Concurrent anxiety, depres-
sion, and posttraumatic stress may contribute to symptoms (Bry-
ant, 2008; Hoge et al., 2008; Stulemeijer et al., 2007), as may other
injuries, pain, and medications (Carroll et al., 2004; Meares et al.,
2006, 2008; Ponsford, 2005). Meares et al. (2006, 2008) found that
a diagnosis of PCS an average of 4.9 days postinjury was just as
likely in trauma controls as it was in patients with mTBI, in
patients admitted to hospital with major trauma, with PCS pre-
dicted by previous affective or anxiety disorder, female gender, IQ,
processing speed, and acute posttraumatic stress symptoms, but
not presence of mTBI. Meares and colleagues (2008) raised doubts
as to whether mild TBI contributes anything to symptoms over and
above these factors. However, it is possible that the effects of
anesthesia and analgesia impacted on findings in this group.
Increased reporting of symptoms may be associated with litiga-
tion or compensation-seeking (Binder & Rohling, 1996; Kashluba
et al., 2008; Paniak et al., 2002). This will in turn depend upon the
cause of injury and context of assessment. In a study focusing on
mTBI cases with disappointing recoveries mostly in a litigation or
compensation context, the variables most strongly related to out-
come were depression, pain, and symptom invalidity on measures
of response bias (Mooney, Speed, & Sheppard, 2005).
Thus it appears that mTBI is a complex condition. Potential
contributing factors relate to preinjury factors (demographic vari-
ables including gender, age, and education; preinjury physical and
psychiatric status; and history of previous head injury), injury-
related factors (presence and severity of mTBI in terms of PTA
duration and GCS, associated cognitive impairments), and the
postinjury coexistence of pain, posttraumatic stress disorder
(PTSD), other forms of anxiety, depression, other life stressors,
and litigation. However, no study has prospectively examined the
relative influence of all these factors in patients with uncompli-
cated mTBI and a general trauma sample recruited in the emer-
gency department (ED) soon after injury not requiring general
anesthesia. Therefore, the aim of this study was to prospectively
examine the influence of the above-mentioned factors on outcome
measured in terms of PCS 1 week and 3 months postinjury. It was
hypothesized, on the basis of previous studies, that injury-related
factors, including presence and severity of a mTBI, would have the
strongest influence on outcome measured in terms of postconcus-
sive symptoms at 1 week postinjury and that ongoing problems at
3 months postinjury would be predicted by a combination of mTBI
presence and severity; psychological factors including anxiety,
depression, pain, and PTSD; and other life stressors. It was con-
sidered important for clinicians to be able to predict, on the basis
of factors known in the ED (i.e., preinjury and injury-related
factors), what the outcome would be at both 1 week and 3 months
postinjury. It was also considered important to be able to identify,
on the basis of status at 1 week postinjury, when patients may be
reviewed clinically, what factors predicted ongoing PCS at 3
months postinjury. Concurrent predictors were examined at each
time point to identify causative factors relating to PCS at each time
point.
Method
The study was conducted as part of a study examining outcome
and the use of a revised version of the Westmead PTA Scale as a
screening tool in patients with mTBI. It was approved by the
305
MILD TRAUMATIC BRAIN INJURY OUTCOME PREDICTORS
Alfred Hospital and Monash University Research Ethics Commit-
tees.
Participants
Participants were recruited consecutively from the Alfred Emer-
gency & Trauma Centre (E&TC) in Melbourne, Australia. Inclu-
sion criteria for the mTBI group included (1) recent (⬍24 hr)
history of trauma to the head, resulting in loss of consciousness
(LOC) ⬍30 minutes, PTA ⬍24 hours, and a GCS score of 13–15
on presentation to the ED; (2) age 18 years or over; and (3) English
speaking. Participants were excluded if they (1) were intubated or
required general anesthesia following injury; (2) had a breath
alcohol reading ⬎.05 at time of recruitment; (3) were under the
influence of illicit substances at the time of injury; (4) had focal
neurological signs, seizures, or intracerebral abnormality on com-
puted tomography (CT); (5) had a dominant upper-limb injury that
precluded use of a computer mouse; (6) were under spinal precau-
tions and not able to sit upright; (7) had a history of previous
cognitive impairment, neurological illness, significant alcohol or
drug abuse or other psychiatric impairment currently affecting
daily functioning; or (8) were unavailable for follow-up. The
trauma control (TC) group comprised patients presenting with
minor injuries not involving the head and no LOC or PTA follow-
ing their injury. Other inclusion and exclusion criteria were the
same as for the mTBI group. Individuals with a medical history of
nonneurological illness (e.g., cardiac disease, hypertension, can-
cer, diabetes), psychiatric history (excluding psychosis), prior
mTBI, and reported alcohol or cannabis use were included in the
study if they did not report any significant preinjury cognitive
difficulties.
Measures
The dependent variable, PCS, was measured using the ImPACT
Post-Concussion Symptom Inventory (Lovell & Collins, 1998)
comprising 22 common concussion symptoms (e.g., headache,
dizziness) with the severity ranging from 0 ⫽none to 6 ⫽severe.
The list is more expansive than the criteria included in ICD-10.
The symptoms were added into a total Post-Concussive Symptoms
summary score, reflecting the number and severity of symptoms.
The following measures were examined as potential predictors
of PCS:
Preinjury factors. Preinjury factors included age in years,
gender, education in years, and previous head injury (yes/no;
number of previous head injuries). Preinjury physical and mental
health was assessed with the SF-36 Health Survey (SF-36; Jen-
kinson, Coulter, & Wright, 1993; Ware & Sherbourne, 1992),
comprising a 36-item questionnaire, yielding an 8-scale health
profile and two summary measures—a Physical Component Score
and a Mental Component Score. Preinjury psychiatric history was
assessed with the Mini-International Neuropsychiatric Interview
(MINI; Sheehan et al., 1998), a brief, reliable and valid structured
diagnostic interview comprising 130 questions, screening for 16
Axis I Diagnostic and Statistical Manual of Mental Disorders (4th
ed.; DSM–IV) disorders and 1 personality disorder. Presence or
absence of a diagnosis in each category was documented.
Injury-related factors. The Glasgow Coma Scale score (Te-
asdale & Jennett, 1976) utilizes the injured person’s best eye-
opening, verbal, and motor responses to assess the conscious state,
with a total score between 3 (showing no response) and 15 (alert
and well oriented).
The PTA duration in days was determined by asking the patient
what his or her first memory was after the injury and what had
happened after that, until the patient could provide detailed and
continuous recall of events after the injury. This was verified by
examination of ambulance and hospital admission notes and dis-
cussion with accompanying persons. Patients were also screened
using the revised Westmead PTA Scale (Ponsford et al., 2000), and
if still in PTA on admission to the ED also had their orientation
and ability to lay down new memories assessed prospectively at
hourly intervals using this measure.
Cognitive performance was determined with the ImPACT con-
cussion battery (Iverson, Lovell, & Collins, 2005), a computer-
administered neuropsychological test battery consisting of five test
modules, testing attention, verbal and visual memory, processing
speed, and RT. Summary scores for each module were used in
analyses.
Postinjury factors.
Pain. The Visual Analogue Scale (VAS) is a brief scale rang-
ing from 0 (no pain)to10(extreme pain) used to measure pain.
The VAS has been commonly used as a brief and convenient
measure of pain for more than 30 years (Huskisson, 1974).
Use of narcotic analgesia. Yes/No
Posttraumatic stress symptoms. The PTSD Checklist—
Specific (PCLS) is a self-report rating scale for assessing the 17
DSM–IV symptoms of PTSD on a 5-point scale from not at all to
extremely. A total symptom severity score (range 17– 85) is ob-
tained by summing scores from the 17 items. The scale has been
comprehensively validated (Blanchard, Jones-Alexander, Buckley,
& Forneris, 1996; Forbes, Creamer, & Biddle, 2001).
Anxiety and Depression. The Hospital Anxiety and Depres-
sion Scale (HADS) is a validated self-assessment scale of current
anxiety and depression symptoms, with 14 questions graded on a
4-point Likert scale (0 –3), yielding separate anxiety and depres-
sion subscale scores of 0 –21. The scale minimizes use of physical
symptoms of mood disorders, which may be present in the med-
ically ill (Snaith & Zigmond, 1986). The validity and reliability of
the HADS has been established in patients with TBI (Schönberger
& Ponsford, 2010; Whelan-Goodinson, Ponsford, & Schönberger,
2009).
Other life stressors. The Revised Social Readjustment Rating
Scale (RSRRS) measures 43 stressful events that happened in the
last 12 months (Holmes & Rahe, 1967; Horowitz, Schaefer, Hi-
roto, Wilner, & Levin, 1977). The total score was recorded. These
scores are interpreted as follows: low stress ⬍149; mild stress ⫽
150 –200; moderate stress ⫽200 –299; major stress ⬎300.
Litigation (yes/no). Participants were asked to indicate
whether (1) they were seeking compensation, (2) claims or charges
had been made against them, and (3) any litigation had been
resolved.
Procedure
Potential mTBI and TC participants were identified on the
computerized E&TC patient list. Patients with mTBI were re-
cruited after they had emerged from PTA, as assessed using the
revised Westmead PTA Scale. After providing informed consent
306 PONSFORD ET AL.
and demographic information, participants completed the acute
assessment at the hospital prior to discharge or, in a few cases, at
home, but within 48 hours of injury. The acute assessment com-
prised a computerized concussion assessment battery (ImPACT)
that also included the PCS to document current symptoms. The
SF-36 was completed because it pertained to their general health
and wellbeing prior to injury. This assessment took 45 min.
At 1 week follow-up, participants in both mTBI and TC groups
completed the ImPACT cognitive battery, PCS measure, SF-36,
HADS, and VAS as they pertained to current functioning. Infor-
mation regarding current capacity for work, study, and functional
activities was also collected. The MINI diagnostic interview was
completed with respect to prevalence of lifetime preinjury psychi-
atric disorders. At the 3-month follow-up, participants repeated the
same assessments. However, the SF-36 examined the participants’
general health over the preceding 4-week period, and the MINI
examined psychiatric status within the 3 months since injury.
Participants also completed the PCL-S to assess postinjury
PTSD symptoms and the RSRRS to measure concurrent life
stressors and reported on current employment status. These
assessments took 1 hr.
Analysis
Data analysis was undertaken with SPSS17 (SPSS, Inc., Chi-
cago, IL), and statistical significance was reported at the 0.05
level. Missing values, of which there were very few, were ex-
cluded from descriptive statistics. Categorical variables were pre-
sented as percentages and continuous variables as medians and
ranges. The main outcome was PCS. Preliminary correlational
analyses were conducted using Spearman’s rho to examine both
the correlations between the variables and PCS and the intercor-
relations of the variables, because only a limited number of vari-
ables could be included in each model, and there was a need to
avoid multicollinearity. Following these analyses, a series of gen-
eralized linear models (GLM) were computed to identify predic-
tors of postconcussive symptoms at 1 week and 3 months postin-
jury. Because GLMs do not exclude cases with missing values, the
only variables excluded were those that contributed to multicol-
linearity. Because the PCS scores were skewed, for use in regres-
sion analysis, PCS scores were grouped into three categories with
equal frequencies. Because the PCS scores declined over time, the
grouping was done separately for PCS scores at 1 week and 3
months as follows: The baseline PCS scores were divided into
ⱕ16, 17–35, and ⱖ36. The PCS scores at 1 week were split into
ⱕ5, 6 –23, and ⱖ24. The PCS scores at 3 months were divided
into 0, 1– 8, and ⬎09. GLM is a flexible approach to multiple
regression that allows it to predict ordinal dependent variables. In
order to do so, ordinal logistic regression was chosen as the link
function in the GLMs.
The GLMs were conducted in three models. Table 1 shows the
predictors that were used in each model. The first model used
information from time of injury to predict outcome, first at 1 week
postinjury and separately at 3 months postinjury. The SF-36 Men-
tal Health scale was removed to avoid collinearity with preinjury
psychiatric status. The second model examined prediction of PCS,
first at 1 week and second at 3 months postinjury on the basis of
information known at 1 week postinjury. SF-36 Mental quality of
life and HADS depression were removed from the model to avoid
collinearity with other variables. Narcotics/analgesics were ad-
justed for only in the PCS 1-week model, because a significant
number of participants were still using these. The third model
examined the influence of both preinjury demographic and health
factors and concurrent factors relating to cognitive function, pain,
PTSD symptoms, general anxiety symptoms, and other life stres-
sors on reported PCS at 3 months postinjury. The model was
conducted to predict PCS at 3 months only. In order to examine
whether the variables predicting outcome differed between mTBI
and TC groups, models predicting 3-month PCS were conducted
for mTBI and TC groups separately, using the same variables as in
the previous models. The relationship between the presence of
preinjury psychiatric disorders and HADS scores 1 week and 3
months postinjury was examined with Student ttest. Group dif-
ferences and changes over time in PCS and HADS were calculated
with Mann–Whitney test, Wilcoxon signed-ranks test, and Fried-
man test because the variables were not normally distributed.
Results
Participants were recruited between January 2007 and January
2009. During this period, 882 potential mTBI participants were
admitted to the E&TC while it was staffed by a mTBI researcher,
including evenings and weekends. Of these, 196 were eligible, and
123 were recruited into the study. Of 1404 potential TC partici-
pants, 338 were eligible and 100 were recruited and completed the
acute assessment. The participant profiles are described in Table 2.
Patients were predominantly young single men injured in motor
Table 1
Predictor Variables for GLM Models
Data
phase Variable Model 1
a
Model 2
a
Model 3
b
Preinjury Gender ✓✓✓
Age ✓✓✓
Psychiatric history (MINI) ✓
Physical health (SF-36) ✓✓
Acute PTA duration ✓✓✓
Verbal memory (ImPACT) ✓
Visual memory (ImPACT) ✓
Group (mTBI/control) ✓✓✓
1 week Verbal memory (ImPACT) ✓
Visual memory (ImPACT) ✓
Pain (VAS) ✓
Physical health (SF-36) ✓
Anxiety (HADS) ✓
Narcotic/analgesics ✓
c
3 months Verbal memory (ImPACT) ✓
Visual memory (ImPACT) ✓
Pain (VAS) ✓
PTSD symptoms (PCLS) ✓
Stressful life events (RSRRS) ✓
Anxiety (HADS) ✓
Note. GLM ⫽generalized linear models; MINI ⫽Mini-International
Neuropsychiatric Interview; SF-36 ⫽Short-Form 36; PTA ⫽posttrau-
matic amnesia; mTBI ⫽mild traumatic brain injury; VAS ⫽Visual
Analogue Scale; HADS ⫽Hospital Anxiety and Depression Scale;
PTSD ⫽posttraumatic stress disorder; PCLS ⫽PTSD Checklist—
Specific; RSRRS ⫽Revised Social Readjustment Rating Scale.
a
Developed to predict PCS at 1 week and 3 months.
b
Developed to
predict PCS at 3 months.
c
Adjusted for only in the PCS at 1-week model.
307
MILD TRAUMATIC BRAIN INJURY OUTCOME PREDICTORS
vehicle collisions. There were no significant group differences in
terms of gender, age, education, marital status, or employment
status, or in history of previous mTBI. The mTBI group more
commonly sustained assault-related injuries than did controls.
More mTBI participants than controls had soft tissue injuries/
lacerations.
At acute ED assessment, 77 (62.6%) TBI and 44 (44%) controls
reported taking narcotic analgesics (p⫽.006). At 1 week, these
numbers dropped to 20 (18.2%) in the TBI group and 19 (21.1%)
in controls without any statistical group difference (p⫽.603). At
3 months the use of narcotic analgesics dropped to 2 patients in
each group (p⫽.905).
Of the 120 mTBI participants with a known LOC status, 111
(92.5%) had a loss of consciousness (LOC) with the median LOC
being 7 s, a mean of 61.44 (SD ⫽110) s, and a range of 0 –10 min.
Overall, 118 (96.7%) TBI participants had a reported period of
PTA, with the median PTA being 15 min, a mean of 103 (SD ⫽
191) min, and the range being 0 –24 hr.
Of the 123 mTBI participants, 111 (90.24%) completed the
1-week assessment, and 90 (73.17%) completed the 3-month
follow-up. Of the 100 TCs, 90 (90%) completed the 1-week
follow-up and 80 (80%) the 3-month follow-up. There was no
significant difference in gender between participants who con-
sented to participate in the study and those who declined (p⫽
.369). However, those who consented to participate were signifi-
cantly older, with a median age of 32 years in comparison with 29
years for decliners (p⫽.008). The subsequent results are pre-
sented for those participants completing the 3-month follow-up
only. The scores for PCS and HADS at each time point at which
they were assessed are set out in Table 3. The groups differed
significantly in terms of reported PCS, both on acute assessment in
the ED and 1-week postinjury, with the mTBI group having more
than double the Post-Concussive Symptom Inventory score of the
control group at both time points. There was a significant decline
in PCS over time. There were no significant differences in overall
reporting of PCS at 3 months postinjury, nor did any particular
symptom differentiate the groups. Applying the ICD-10 criteria
used by Meares et al. (2008), 45.5% of mTBI participants and
14.0% of TCs reported a score of 4 or more on three or more of the
ICD-10 symptoms at acute assessment in the ED (p⬍.001).
However, neither these criteria nor any other cut-off score for PCS
significantly differentiated the mTBI and TC groups at 1 week or
3 months postinjury. Groups did not differ on the HADS at acute
assessment, 1 week, or 3 months postinjury. There was a signifi-
cant reduction in anxiety and depression symptoms in both groups
over time. More detailed results obtained by the mTBI and TC
Table 2
Profile of Patients by Group
Demographics mTBI (n⫽123) TC (n⫽100)
Age (years)
a
31 (18–72) 32 (19–66)
Education (years)
a
13 (14–22) 14 (9–20)
Gender (male)
b
91 (74) 64 (64)
Married/de facto
b
47 (38.2) 41 (40)
Employment status
b
Full time 96 (78) 84 (84)
Part time 9 (7.3) 2 (2)
Casual 4 (3.3) 9 (9)
Student 3 (2.4) 2 (2)
Not working 11 (8.9) 3 (3)
Cause of injury
b
Assault 16 (13.3)
ⴱ
2 (2)
Motor vehicle collision
c
49 (40.9) 28 (28)
Bicycle collision 24 (20) 18 (18)
Fall 15 (12.5) 23 (23)
Sport injury 10 (8.3) 11 (11)
Other 9 (7.3) 18 (18)
Type of injury
b
Soft tissue/laceration 97 (78.9)
ⴱⴱ
59 (59)
Fracture 21 (17.1) 21 (21)
Ligamentous 5 (4.1) 19 (19)
Dislocation 0 (0) 1 (1)
Involved in litigation
b
15 (17.2) 7(8.9)
History of head injury
b
51 (41.5) 28 (28)
Note. Chi-square tests. TC ⫽trauma control; mTBI ⫽mild traumatic
brain injury.
a
Values are given as median (range).
b
Values are given as N(percent-
age).
c
This category includes motor vehicle, motorcycle, and pedestrian
hit by vehicle collisions.
ⴱ
p⫽.001.
ⴱⴱ
p⬍.001.
Table 3
Postconcussive Symptom (PCS) Scores and HADS Scores by Group at Each Time Point
Measure Time point
mTBI (n⫽90) TC (n⫽80)
pMedian
a
(min-max) Mean Median
a
(min-max) Mean
PCS total Acute 32.5 (0–86) 37.88 13.5 (0–97) 19.1 ⬍.001
1 week 16 (0–97) 22.13 7.5 (0–78) 15.85 .019
3 months 4 (0–81)
b
10.36 4 (0–81)
c
9.57 .424
HADS Anxiety 1 week 5 (0–17) 5.28 4 (0–16) 5.04 .527
3 months 3 (0–16)
d
4.02 2 (0–16)
e
3.38 .407
HADS Depression 1 week 3 (0–18) 4.35 3 (0–14) 3.75 .267
3 months 1 (0–16)
f
2.4 1 (0–11)
g
1.59 .058
Note. Probability values for the group comparisons are presented in the last column, and within-subject comparison results are provided in superscript
below the tables. HADS ⫽Hospital Anxiety and Depression Scale; TC ⫽trauma control; mTBI ⫽mild traumatic brain injury.
a
Median is given as minimum–maximum.
b
p⬍.001 Friedman test showing decline in PCS over time in mTBI patients.
c
p⬍.001 Friedman test
showing decline in PCS over time in controls.
d
p⫽.002 Wilcoxon signed-rank test showing a drop in HADS Anxiety over time in mTBI patients.
e
p⬍
.001 Wilcoxon signed-rank test showing a drop in HADS Anxiety over time in controls.
f
p⬍.001 Wilcoxon signed-rank test showing decline in HADS
Depression over time in mTBI patients.
g
p⬍.001 Wilcoxon signed-rank test showing decline in HADS Depression over time in mTBI patients.
308 PONSFORD ET AL.
participants on each of the variables are detailed in another article
(Ponsford, Cameron, Fitzgerald, Grant, & Mikocka-Walus, 2011).
Predictors of Postconcussive Symptoms
Preliminary correlational analyses revealed no significant associa-
tion between education and PCS at 1 week (r ⫽⫺.036, p⫽.618) or
3 months postinjury (r ⫽⫺.074, p⫽.345). History of previous head
injury was not significantly associated with PCS at 1 week (r⫽.052,
p⫽.469) or 3 months postinjury (r ⫽⫺.048, p⫽.540). Nor was
there a significant association between seeking compensation/
litigation and reported PCS at 3 months postinjury (r⫽.081, p⫽
.298), with few participants seeking compensation. These variables
were therefore not included in the predictive models.
Regarding the cognitive variables, as described by Ponsford et al.
(2011), the mTBI participants differed significantly from TCs in
performance on the ImPACT Visual Memory index only, whereas the
group difference on Verbal Memory approached significance. There
were no group differences apparent on the other scales. Moreover,
these two variables showed the strongest correlations with PCS of
each of the ImPACT summary scores (1-week Verbal Memory com-
posite with 3-month total PCS: r⫽⫺.206, p⫽.007; 1-week Visual
Memory composite with 3-month total PCS: r⫽⫺.129, p⫽.097).
Therefore, giving consideration to the potential for multicollinearity
and the limitations on the number of variables that could be included
in the regression analyses, these were the two cognitive measures
from ImPACT selected for use in the regressions.
Examination of the intercorrelations of predictor variables re-
vealed that initial GCS was significantly associated with PTA
duration (r⫽.572, p⬍.001). To avoid multicollinearity, we did
not include GCS in the analyses, because PTA showed a stronger
association with PCS. The preinjury SF-36 Mental Component
score was significantly correlated with the SF-36 Physical Com-
ponent score (⫺.328, p⬍.001) and with preinjury MINI neuro-
psychiatric status (⫺.377, p⬍.001). Because the latter showed a
stronger correlation with PCS, the SF-36 Mental Component score
was excluded from the regressions. Additionally, there were sig-
nificant correlations between the HADS anxiety and depression
scores (r⫽.670, p⬍.001). Because HADS anxiety was more
strongly associated with PCS, to avoid multicollinearity, we in-
cluded only the HADS anxiety score as a predictor.
Prediction of 1-Week PCS From Preinjury and Acute
Injury Predictors
For Model 1a (ED/acute predictors), the significant predictors of
a higher PCS score at 1-week postinjury were having had a mTBI,
gender and preinjury psychiatric history, with participants with
mTBI (odds ratio [OR] ⫽3.25, p⫽.001), women (OR ⫽2.56,
p⫽.004), and those with psychiatric history (OR ⫽3.7, p⬍.001)
at a higher risk of PCS at 1 week. Other variables used in the
model that were not significantly predictive were acute cognitive
memory measures (ImPACT Verbal Memory score, acute Im-
PACT Visual Memory score), as well as PTA duration, age, and
preinjury SF-36 Physical Health.
Prediction of 3-Month PCS From Preinjury and
Acute Injury Predictors
For Model 1b (ED/acute predictors), the significant predictors of
higher PCS score at 3 months postinjury were presence of prein-
jury psychiatric history (OR ⫽2.56, p⫽.006) and lower preinjury
Physical Health on the SF-36 (OR ⫽1.09, p⫽.004), with mTBI
no longer a significant predictor. Again, acute cognitive measures
of memory as well as Group (mTBI vs. TC), gender, age, and PTA
duration were not associated with PCS at 3 months.
Prediction of PCS at 1 Week From Injury-Related and
Concurrent Measures at 1 Week
For Model 2a (1-week variables), the significant predictor of a
higher PCS score at 1 week were having had a mTBI (OR ⫽3.30,
p⬍.001), more anxiety symptoms on the HADS (OR ⫽1.32, p⬍
.001), and greater pain severity on the VAS (OR ⫽1.03, p⬍
.001). Again, 1-week ImPACT Verbal Memory and Visual Mem-
ory scores—as well as gender, age, preinjury SF-36 Physical
Health, PTA duration, and 1-week narcotic analgesia—were not
significantly predictive.
Prediction of PCS at 3 Months From Injury-Related
and 1-Week Variables
For Model 2b (1-week variables predicting outcome at 3
months), having a mTBI was no longer a significant predictor of
higher PCS score at 3 months postinjury. However, presence of
more anxiety symptoms on the HADS at 1 week remained a highly
significant predictor of 3-month PCS (OR ⫽1.18, p⬍.001).
One-week assessments on ImPACT Verbal and Visual Memory
measures as well as gender, age, preinjury SF-36 Physical Health,
PTA duration, and VAS pain at 1 week were not significant
predictors of 3-month PCS.
Prediction of PCS at 3 Months From Injury-Related
and Concurrent 3-Month Variables
For Model 3 (3-month variables), again having a mTBI was no
longer a significant predictor of 3-month PCS, nor were 3-month
ImPACT Verbal and Visual Memory scores, gender, age, preinjury
SF36 Physical Health, or PTA duration. The significant concurrent
predictors or indicators were a higher anxiety symptom score on
the HADS (OR ⫽1.31, p⫽.002), greater VAS pain severity
(OR ⫽1.04, p⫽.04), presence of more PTSD symptoms on the
PCLS (OR ⫽1.09, p⫽.03), and other stressful life events on the
RSRRS (OR ⫽1.001, p⫽.02).
Prediction of PCS at 3 Months for mTBI and Trauma
Control Groups Separately
The final models examined predictors of PCS at 3 months
postinjury for each group separately. In the model including only
mTBI participants, the significant predictors were HADS anxiety
symptoms (OR ⫽1.42, p⫽.01) and higher age (OR ⫽1.07, p⫽
.04). In the model including only TC participants, the significant
predictors were presence of PTSD symptoms on PCLS (OR ⫽
1.23, p⫽.04) and other life stressors on the RSRRS (OR ⫽1.001,
p⫽.02). Three-month ImPACT Verbal and Visual Memory
scores, along with gender, preinjury SF-36 Physical health, PTA
duration, and 3-month VAS pain, were not significant predictors of
3-month PCS in either group.
309
MILD TRAUMATIC BRAIN INJURY OUTCOME PREDICTORS
An analysis of the bivariate relationship between the presence of
preinjury psychiatric disorders and HADS scores 1 week and 3
months postinjury revealed that HADS anxiety scores at 1 week
were associated with greater likelihood of a preinjury psychiatric
disorder, t(1, 75) ⫽⫺2.500, p⫽.013, whereas HADS Depression
scores did not show such an association. HADS anxiety and
depression scores at 3 months postinjury were not significantly
associated with preinjury psychiatric disturbances.
Discussion
This study of predictors of outcome in individuals with uncom-
plicated mTBI and general trauma not requiring surgery found that
mTBI predicted PCS during the acute phase after injury, but not at
3 months postinjury. It also found that premorbid psychiatric
factors and postinjury anxiety were the strongest predictors of
persistent symptoms at 3 months postinjury.
Three factors contributed uniquely to reporting of PCS at 1
week after injury—namely, having experienced a mTBI, presence
of a preinjury psychiatric disorder, and being female. The finding
is in some respects consistent with the findings of Meares and
colleagues (2008) in identifying the association between preinjury
psychiatric disturbance, female gender, and reported PCS soon
after injury. However, the present study, by focusing on trauma
groups who were well-matched but had less-complex injuries and
had had no surgery since injury, has identified that the experience
of a mTBI also renders the person more than three times as likely
to experience PCS in the first week postinjury than a general
trauma patient without mTBI. Therefore it would seem erroneous
to conclude that mTBI does not cause PCS in the early days after
injury. As has been found in some previous studies, one of the
traditional markers of injury severity, namely, duration of PTA,
was not associated with reported PCS either at 1 week or 3 months
after injury. Moreover, performance on the ImPACT cognitive
concussion battery, specifically the Verbal and Visual memory
modules, also failed to predict PCS both at 1 week and 3 months
postinjury (Carroll et al., 2004; Meares et al., 2006, 2008; Ponsford
et al., 2000; Stulemeijer, van der Werf, Borm, & Vos, 2008),
despite the fact that mTBI participants did perform more poorly on
the ImPACT Visual Memory index at both of these time points.
Some previous studies have found other neuropsychological tests
to be sensitive to effects of mTBI in the early stages after injury,
including tests of visual RT, Digit Symbol Coding, the Speed of
Comprehension Task, and Paced Auditory Serial Addition Task
when administered in the early days after injury, with some studies
also showing impairment on tests of visual or verbal memory
(Carroll et al., 2004; Kwok, Lee, Leung, & Poon, 2008; Malojcic,
Mubrin, Coric, Susnic & Spilich, 2008; Peterson et al., 2009;
Ponsford et al., 2000; Vanderploeg, Curtiss, & Belanger, 2005).
However, there is limited evidence that administration of these
tests is predictive of PCS in either the short or the long term. The
administration of computerized neuropsychological tests in the
acute setting does not appear to be helpful in the management of
patients with uncomplicated mTBI.
Neither education nor history of previous head injury was as-
sociated with PCS at 1 week or 3 months postinjury. Older age
emerged as a predictor in the mTBI group only at 3 months
postinjury. It was also clear that litigation was not a factor that
contributed to reporting of PCS. This possibly reflects the low
proportion of participants engaged in litigation. The influence of
litigation may only appear when recruitment occurs in that context,
as was the case in the study by Mooney and colleagues (2005).
PCS reporting was more strongly associated with the injured
person’s anxiety levels at 1 week postinjury, which was in turn
associated with preinjury psychiatric history. It is possible that the
experience of PCS resulted in heightened anxiety in individuals
with a psychiatric history, who may have greater anxiety sensitiv-
ity and less adaptive coping mechanisms or stress tolerance. The
symptoms experienced then caused anxiety, which might have
further exacerbated symptoms. In support of this contention is the
finding that reporting more anxiety symptoms on the HADS at 1
week postinjury was associated with greater likelihood of persist-
ing PCS 3 months postinjury.
This finding supports that of previous studies by Dischinger et
al. (2009) in which early symptoms of anxiety, noise sensitivity,
and trouble thinking predicted long-term PCS 3 months postinjury,
with women who reported anxiety early after injury being most
likely to develop ongoing PCS. Stulemeijer and colleagues (2008)
also found that emotional distress was significantly associated with
continuing cognitive complaints 6 months postinjury, along with
lower education, personality, and poor physical functioning, espe-
cially fatigue. This suggests that individuals showing high levels of
anxiety symptoms early after injury may be targeted for preven-
tative intervention. As suggested by Mittenberg, Tremont, Zielin-
ski, Fichera, and Rayles (1996), the injured person’s appraisal or
attribution of symptoms may play a role in perpetuating them.
Mittenberg and colleagues (1996) and Cicerone (2002) have ad-
vocated for the use of cognitive behavior therapy (CBT) to en-
courage patients to change their inner dialogue to develop a sense
of mastery over symptoms and take control of their lifestyle, by
using thought stopping, replacing negatively biased thoughts, and
encouraging return to rewarding activities. Hodgson and col-
leagues (Hodgson, McDonald, Tate, & Gertler, 2005) showed that
CBT may reduce social anxiety following mTBI. While Ghaffar,
McCullagh, Ouchterlony, and Feinstein (2006) found no signifi-
cant overall advantage in the provision of routine multidisciplinary
treatment and follow-up to all individuals with mTBI, individuals
with preexisting psychiatric problems did benefit from the inter-
vention. We would therefore propose that individuals with a his-
tory of psychiatric disorder and those showing high levels of
anxiety at 1 week after mTBI may be targeted for cognitive–
behavioral interventions. There is a need for further evaluation of
such intervention models, however.
By 3 months postinjury the experience of a mTBI did not contrib-
ute uniquely to reported PCS, which was most strongly associated
with the experience of PTSD symptoms and other stressors, anxiety,
and pain. However, it should be noted that the frequency of a score
indicative of a formal diagnosis of PTSD was not high in either group
(n⫽7 in mTBI and 3 in TC group). Moreover, the fact that the
predictors of PCS differed between the mTBI and TC groups at 3
months postinjury suggests that there may have been differing sources
of anxiety, with PTSD symptoms and other life stressors most sig-
nificant for the TCs, but older age and the presence of anxiety on the
HADS showing a stronger association for mTBI participants. The
higher HADS anxiety scores may have been a response to the expe-
rience of injury-related symptoms. This is also supported by the
finding of greater self-reported concentration and memory difficulties
affecting daily activities in the mTBI group in relation to TCs, as
310 PONSFORD ET AL.
reported by Ponsford and colleagues (2011). However, one cannot be
sure of the direction of this association, and further investigation of
this is warranted.
This study focused on individuals with mTBI with no focal neu-
rological signs, nor evidence of injury on CT scan and who were not
under the influence of illicit substances or requiring general anesthe-
sia. We did this to exclude extraneous causes of cognitive impairment.
This sample represents the very mildest end of the mTBI spectrum
and cannot be said to represent individuals with complicated mTBI
for whom predictors of outcome may differ. The sample who partic-
ipated was also slightly older than the group that did not agree to
participate, and one cannot rule out the possibility that this in some
way influenced the findings, given that age proved to be a significant
predictor in the model predicting 3-month outcome in the TBI group.
Moreover, given the number of statistical comparisons, we cannot
rule out the possibility of Type I error.
Taking into account these factors, we believe that this study has
demonstrated that the presence of a mTBI does contribute signifi-
cantly to PCS within the acute stages after injury in patients with
uncomplicated trauma, but not to longer-term PCS, which were more
strongly predicted by premorbid psychiatric factors and postinjury
anxiety. Individuals with a preinjury psychiatric history appear to
respond to the experience of mTBI and PCS with greater anxiety,
which may, in turn, exacerbate their PCS. The effects of mTBI are
thus complex and multifactorial. If we are to improve management of
this condition, we need to acknowledge this complexity, and equip
individuals with information and coping strategies to minimize the
development of anxiety.
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Received September 7, 2010
Revision received September 9, 2011
Accepted September 12, 2011 䡲
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