[show abstract][hide abstract] ABSTRACT: OBJECTIVE: An association between bipolar disorder and cognitive impairment has repeatedly been described, even for euthymic patients. Findings are inconsistent both across primary studies and previous meta-analyses. This study reanalysed 31 primary data sets as a single large sample (N = 2876) to provide a more definitive view. METHOD: Individual patient and control data were obtained from original authors for 11 measures from four common neuropsychological tests: California or Rey Verbal Learning Task (VLT), Trail Making Test (TMT), Digit Span and/or Wisconsin Card Sorting Task. RESULTS: Impairments were found for all 11 test-measures in the bipolar group after controlling for age, IQ and gender (Ps ≤ 0.001, E.S. = 0.26-0.63). Residual mood symptoms confound this result but cannot account for the effect sizes found. Impairments also seem unrelated to drug treatment. Some test-measures were weakly correlated with illness severity measures suggesting that some impairments may track illness progression. CONCLUSION: This reanalysis supports VLT, Digit Span and TMT as robust measures of cognitive impairments in bipolar disorder patients. The heterogeneity of some test results explains previous differences in meta-analyses. Better controlling for confounds suggests deficits may be smaller than previously reported but should be tracked longitudinally across illness progression and treatment.
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Evidence of associations between neurocognitive function and cannabis use in schizophrenia is inconclusive. However, direct measures of cannabis intake and premorbid function are rarely explored in this context. We investigated the relation between cannabis use, determined by its presence in urine, and neurocognitive functioning in schizophrenia controlling for the potential bias of premorbid functioning. METHODS: Naturalistic study of 364 patients with schizophrenia spectrum disorder from catchment areas in Oslo, Norway. Hierarchical multiple regression analyses were used to assess the relationship between cannabis in urine and measures of neurocognitive functioning, with adjustment for confounders, including premorbid functioning. RESULTS: Cannabis was detected in the urine of 21 patients, who had significant dysfunction in several neurocognitive domains independent of a current diagnosis of cannabis abuse. However, level of premorbid functioning explained the associations for all measures. CONCLUSION: Differences in premorbid functioning may explain apparent differences in neurocognitive function between schizophrenia spectrum patients using cannabis or not. The findings suggest that illness-related traits present early in life can affect both later cannabis use and neurocognition, probably by complex mechanisms.
Schizophrenia Research 11/2012; · 4.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Jónsdóttir H, Opjordsmoen S, Birkenaes AB, Simonsen C, Engh JA, Ringen PA, Vaskinn A, Friis S, Sundet K, Andreassen OA. Predictors of medication adherence in patients with schizophrenia and bipolar disorder. Objective: To investigate potential risk factors for medication non-adherence in patients with schizophrenia and bipolar disorder. Method: A total of 255 patients underwent clinical assessments, neurocognitive testing and blood sampling. The patients were divided into groups of 'No', 'Partial' or 'Full' adherence. Relationships to different risk factors were analyzed. Results: In schizophrenia, use of illicit substances, alcohol and poor insight were related to worse adherence. Schizophrenia patients with No adherence did better on tests of executive functioning, verbal learning and memory and had higher IQ than patients with better adherence. There were higher levels of autonomic side effects in the non-adherence group, but body mass index was lower in the Partial adherence group than in the Full adherence group. In the bipolar disorder patients, there was an association between the use of illicit substances and alcohol and poor adherence. We found no relationship between adherence behavior and neurocognition in the bipolar disorder group. Conclusion: Substance use is an important risk factor for non-adherence in patients with schizophrenia and bipolar disorder. Poor insight is also a risk factor in schizophrenia. The results suggest that cognitive dysfunction is not a risk factor for non-adherence in these diagnostic groups.
[show abstract][hide abstract] ABSTRACT: Cognitive dysfunction in bipolar disorder (BD) is well established in the literature; however, there are few studies of neurocognition in patients early in the course of the illness. In this study we compare neurocognitive function in a cohort of first-contact mania patients with a healthy control group matched for age, gender, and education.
Patients with a first manic episode (FM) (n = 34) or previous untreated manic episodes (PM) (n = 21) were neuropsychologically tested following their first treated manic episode. A total of 110 matched healthy control comparison subjects were also tested. The following cognitive domains were evaluated: verbal and visual learning and memory, attention, processing speed, executive functioning, and IQ. Results were corrected for speed of processing differences and were compared with previously reported results for multiple-episode BD patients.
BD patients early in their disease course showed impairments in psychomotor speed, attention, learning and memory, executive functioning, and IQ. When controlling for speed of processing, measures of visuoconstructive reasoning and motor dexterity remained statistically significant. Eighteen percent of FM and 16% of PM patients were found to have clinically significant neurocognitive impairment. No significant relationship between clinical symptoms and neurocognition was found. The first-contact mania patients studied were found to have smaller neurocognitive deficits compared to multiple-episode patients in previous studies.
Neurocognitive dysfunction is present in early BD and is clinically significant for a proportion of patients. Our findings also suggest that neurocognitive dysfunction may increase with illness progression.
[show abstract][hide abstract] ABSTRACT: To investigate sex differences in neurocognition and social functioning in schizophrenia and bipolar disorder and the possible role of sex as a moderator of this relationship.
Participants with schizophrenia (60 women/94 men), bipolar I disorder (55 women/51 men), and healthy controls (158 women/182 men) were assessed with an extensive neuropsychological test battery and a social functioning questionnaire.
We found significant main effects of sex for neuropsychological tests (p < .001, η² = 0.10) and social functioning (p < .001, η² = 0.05), with men scoring below women. Women performed better than men for all neuropsychological tests (except attention and working memory). Both clinical groups performed below healthy controls for all neuropsychological tests (except attention). Post hoc comparisons of persons with schizophrenia and healthy controls yielded significant interaction effects (p < .05) for three neuropsychological tests (California Verbal Learning Test II [CVLT-II], Color-Word Interference, and Interference/Switching), with men with schizophrenia being disproportionally disadvantaged compared with their female counterparts. Regression analyses investigating sex as a moderator between neurocognition and social functioning showed that neurocognition predicted social functioning in schizophrenia, whereas sex predicted social functioning in healthy controls. Sex was not a moderator in any of the three groups.
This study is the first to find neurocognitive sex differences for bipolar disorder and replicated previous findings for schizophrenia. The data did not support the hypothesis that sex is a moderator between neurocognition and social functioning. Clinical implications include the use of different cognitive remediation strategies based on sex.
[show abstract][hide abstract] ABSTRACT: Patients with schizophrenia exhibit distorted beliefs and experiences, and their own evaluation of this is labeled cognitive insight. We examined the relationship between cognitive insight and neurocognition, as well as the contribution of neurocognition in explaining cognitive insight.
Clinically characterized patients with schizophrenia (n=102) were assessed with a measure of cognitive insight, Beck Cognitive Insight Scale (BCIS) and a neuropsychological test battery. The contribution of neurocognition to the explained variance in BCIS components self-reflectiveness (i.e. objectivity and reflectiveness) and self-certainty (i.e. overconfidence in own beliefs) was examined controlling for current affective and psychotic symptoms.
A significant negative correlation was found between self-certainty and verbal learning, whereas no associations were found between self-reflectiveness and any of the neuropsychological tests. Verbal learning was added significantly to the explained variance in self-certainty after controlling for potential confounders.
High self-certainty was associated with poor verbal learning. This suggests that overconfidence in own beliefs is associated with cognitive dysfunction in schizophrenia.
Progress in Neuro-Psychopharmacology and Biological Psychiatry 03/2011; 35(4):1059-63. · 3.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aim of this study was to investigate whether suicide attempters had higher IQ, better executive functioning, or were more impulsive as measured by neuropsychological tests than non-attempters in a group of patients with schizophrenia spectrum disorders.
One hundred seventy-four patients with schizophrenia spectrum disorders were assessed with a clinical interview for diagnosis, suicidality, symptoms and function, and underwent an extensive neurocognitive test battery.
There were no statistically significant differences in any neurocognitive domains between lifetime suicide attempters and non-attempters, or between patients with different rates of suicide attempts. Currently suicidal patients were significantly more impulsive (had poorer inhibitory control) than currently non-suicidal patients, but this difference was mediated by positive psychotic symptoms.
The findings indicate that among patients with schizophrenia spectrum disorders, there are no significant differences in IQ or neurocognitive functioning between suicide attempters and non-attempters.
[show abstract][hide abstract] ABSTRACT: Studies of social functioning in severe mental disorders are disadvantaged by the multitude of different assessment instruments in use. The present study aims to establish reliability and validity of the Norwegian version of the Social Functioning Scale (SFS) and to examine social functioning in bipolar disorder (BD) compared to schizophrenia (SZ) and healthy controls (HC). SFS, a 76 item questionnaire divided into seven subscales measuring various aspects of daily life functioning, was administered to samples diagnosed with BD (n = 100) or SZ (n = 100) and to HC (n = 100), recruited from the ongoing Tematic Organized Psychosis (TOP) study. Reliability analyses prove adequate psychometric properties both for the composite full scale score (α: 0.81) as well as for the seven subscale scores (α: 0.60-0.88). Principal component analysis of the subscales confirms a one-component structure, explaining 59% of the variance. Although significantly correlated with the Global Assessment of Functioning, our results indicate that the SFS measures different aspects of social functioning, is less influenced by demographic and clinical characteristics, but differentiates at the same time significantly BD from SZ. Thus, SFS adds valuable information as a supplement to standard clinician-rated assessment tools of social functioning, suited both for research and clinical work.
Scandanavian Journal of Psychology 12/2010; 51(6):525-33. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: In line with a dimensional approach to psychopathology, we examined whether psychosocial function and its relationship to neurocognition and clinical symptoms differ across schizophrenia and bipolar disorder subgroups with and without a history of affective or psychotic episodes. From the TOP study, a heterogeneous sample of individuals with schizophrenia spectrum disorders without (n = 60) and with a history of affective episodes (n = 54); individuals with bipolar spectrum disorders with (n = 64) and without a history of psychosis (n = 56) and healthy controls (n = 268) participated. Psychosocial functioning was measured with the Social Functioning Scale (self-rated) and the Global Assessment of Functioning Scale (clinician-rated), neurocognition with a comprehensive neuropsychological test battery, and symptoms with Inventory of Depressive Symptomatology, Young Mania Rating Scale, and Positive and Negative Syndrome Scale. Clinician-rated functioning was poorer in schizophrenia groups than in bipolar groups, but self-rated functioning was similar across all clinical groups and poorer than in controls. Neurocognition and current clinical symptoms were associated with psychosocial function in bivariate analyses, but current symptoms had a greater independent contribution to functioning than neurocognition across clinical groups in multivariate analyses. Despite differences in neurocognition and psychosocial function, groups showed the same pattern in prediction of functioning irrespective of DSM-IV or clinical definition.
Journal of the International Neuropsychological Society 09/2010; 16(5):771-83. · 2.70 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cannabis use is associated with altered neurocognitive functioning in severe mental disorders, but data are still inconclusive and there are no studies of bipolar disorder. The aim of this study was to investigate the association between cannabis use and neurocognition in bipolar disorder compared with schizophrenia in a naturalistic setting.
A total of 133 patients with bipolar disorder and 140 patients with schizophrenia underwent neuropsychological assessments and clinical characterization including measures of substance use. Relationships between cannabis users and neurocognitive function were explored in the two diagnostic groups. Possible interactions between diagnosis and cannabis use were investigated, and findings were controlled for possible confounders.
In bipolar disorder subjects, cannabis use was associated with better neurocognitive function, but the opposite was the case for the schizophrenia subjects. There was a statistically significant interaction effect of diagnosis and cannabis use on focused attention (p=0.019), executive functioning (verbal fluency--set shifting) (p=0.009), logical memory-learning (p=0.007) and on logical memory-recall (p=0.004). These differences in neurocognitive function could not be explained by putative confounders.
The findings suggest that cannabis use may be related to improved neurocognition in bipolar disorder and compromised neurocognition in schizophrenia. The results need to be replicated in independent samples, and may suggest different underlying disease mechanisms in the two disorders.
Psychological Medicine 11/2009; 40(8):1337-47. · 5.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Neurocognitive dysfunction is milder in bipolar disorders than in schizophrenia spectrum disorders, supporting a dimensional approach to severe mental disorders. The aim of this study was to investigate the role of lifetime history of psychosis for neurocognitive functioning across these disorders. We asked whether neurocognitive dysfunction in bipolar and schizophrenia spectrum disorders depends more on history of psychosis than diagnostic category or subtype.
A sample of individuals with schizophrenia (n=102), schizoaffective disorder (n=27), and bipolar disorder (I or II) with history of psychosis (n=75) and without history of psychosis (n=61) and healthy controls (n=280), from a large ongoing study on severe mental disorder, were included. Neurocognitive function was measured with a comprehensive neuropsychological test battery.
Compared with controls, all 3 groups with a history of psychosis performed poorer across neurocognitive measures, while the bipolar group without a history of psychosis was only impaired on a measure of processing speed. The groups with a history of psychosis did not differ from each other but performed poorer than the group without a history of psychosis on a number of neurocognitive measures. These neurocognitive group differences were of a magnitude expected to have clinical significance. In the bipolar sample, history of psychosis explained more of the neurocognitive variance than bipolar diagnostic subtype.
Our findings suggest that neurocognitive dysfunction in bipolar and schizophrenia spectrum disorders is determined more by history of psychosis than by Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) diagnostic category or subtype, supporting a more dimensional approach in future diagnostic systems.
[show abstract][hide abstract] ABSTRACT: Learning potential, a dynamic multi-administration approach to assessment, is claimed to predict functional outcome in schizophrenia better than traditional single-administration neuropsychological tests.
This study investigates the relation between learning potential and clinical and demographic variables, social functioning and neuropsychological abilities in a sample of 30 participants with schizophrenia with a mean IQ score within the normal range (mean Wechsler Abbreviated Scale of Intelligence (WASI) IQ=106).
Two Wisconsin Card Sorting Test (WCST) based methods for assessing learning potential are compared.
The dimensional approach (calculation of gain scores following training) identified one aspect of executive functioning (set shifting) to be related to learning potential. Associations with other neuropsychological tests and social functioning were however limited. The categorical approach (separating high-achievers from learners and non-learners) was not sensitive within this normal IQ sample.
Although there seems to be a relation between learning potential and some aspects of executive functioning, the two existing WCST methods should be used with caution when assessing learning potential in individuals with schizophrenia who have IQ scores within the normal range.
Nordic journal of psychiatry 05/2009; 63(5):405-11. · 0.99 Impact Factor
[show abstract][hide abstract] ABSTRACT: The underlying nature of negative symptoms in psychosis is poorly understood. Investigation of the relationship between the different negative subsymptoms and neurocognition is one approach to understand more of the underlying nature. Apathy, one of the subsymptoms, is also a common symptom in other brain disorders. Its association with neurocognition, in particular executive functioning, is well documented in other brain disorders, but only studied in one former study of chronic patients with schizophrenia. This study investigates the association between apathy and neurocognitive functioning in patients with first episode psychosis (FEP), with the hypothesis that apathy is more associated with tests representing executive function than tests representing other neurocognitive domains.
Seventy-one FEP patients were assessed with an extensive neuropsychological test battery. Level of apathy was assessed with the abridged Apathy Evaluation Scale (AES-C-Apathy).
AES-C-Apathy was only significantly associated with tests from the executive domain [Semantic fluency (r = .37, p < .01), Phonetic fluency (r = .25, p < .05)] and working memory [Letter Number Span (r = .26; p =< .05)]; the first two representing the initiation part of executive function. Confounding variables such as co-occuring depression, positive symptoms or use of antipsychotic medication did not significantly influence the results.
We replicated in FEP patients the relationship between apathy and executive functioning reported in another study for chronic patients with schizophrenia. We also found apathy in FEP to have the same relationship to executive functioning, as assessed with the Verbal fluency tests, as that reported in patients with other brain disorders, pointing to a common underlying nature of this symptom across disorders.
[show abstract][hide abstract] ABSTRACT: The purpose of the study was to investigate the relationship between the symptoms delusions and hallucinations measured by the Positive and Negative Syndrome Scale and cognitive insight as assessed with the Beck Cognitive Insight Scale (BCIS) in patients with schizophrenia. The BCIS is based on 2 subscales, self-reflectiveness and self-certainty, measuring objectivity, reflectiveness and openness to feedback, and mental flexibility. Overall cognitive insight was defined as the difference between self-reflectiveness and self-certainty. This cross-sectional study of 143 patients showed that the occurrence of delusions is associated with low self-reflectiveness and high self-certainty, reflecting low cognitive insight. Hallucinations in the absence of delusions were associated with high self-reflectiveness and low self-certainty, possibly reflecting more open-mindedness and higher cognitive insight. The present findings suggest that delusions are associated with low cognitive insight, whereas solitary hallucinations may be associated with high cognitive insight.
[show abstract][hide abstract] ABSTRACT: This study examined the potential of using the regular administration of a common neuropsychological test, the CVLT-II, to assess learning potential in schizophrenia. Based on List A trial 1 performance and the learning slope, a schizophrenia sample was divided into three learning potential groups (non-learners, learners and high-achievers) that differed in the use of learning strategies. High-achievers utilized more semantic clustering than learners and non-learners, and non-learners were less consistent in words recalled than the other two groups. This standard administration approach is a promising, time-saving alternative to the modified tests of learning potential used so far.
Scandanavian Journal of Psychology 05/2008; 49(2):179-86. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Social cognition and learning potential have been proposed as mediating variables between neurocognition and functional outcome in schizophrenia. The present study examined this relation in a schizophrenia group (N = 26) with normal IQ. Neurocognition was measured with a composite score from tests of verbal learning, psychomotor speed, and executive functioning. Functional outcome was defined as social problem-solving skills and assessed with a role-play test. Social cognition was indexed by tests of visual and auditory emotion perception; and learning potential by estimating a gain score using a triple administration of the WCST. Neurocognition was confirmed to be a strong predictor of social problem-solving, and emotion perception was related to both neurocognition and social problem-solving. When controlling for emotion perception, the association between neurocognition and social problem-solving was weakened, implying a mediating role of emotion perception. Learning potential was not significantly related to neurocognition or social problem-solving, and thus not found to mediate the studied relation. In conclusion, our study indicates that emotion perception is a mediator between neurocognition and functional outcome as assessed with a social problem-solving task and thus a key factor in understanding functional outcome of schizophrenia.
Journal of the International Neuropsychological Society 04/2008; 14(2):279-88. · 2.70 Impact Factor
[show abstract][hide abstract] ABSTRACT: Studies on neurocognitive functioning in bipolar disorder, reporting deficits in memory, attention, and executive functioning, have primarily focused on bipolar I disorder. The aim of this study was to examine whether patients with bipolar I and bipolar II disorder have different neurocognitive profiles.
Forty-two patients with bipolar I disorder, 31 patients with bipolar II and 124 healthy controls, from a large ongoing study on psychotic disorders, were included. Neurocognitive function was measured with a comprehensive neuropsychological test battery.
The bipolar I group performed significantly poorer than the healthy control group and the bipolar II group on all measures of memory. Compared with the control group, the bipolar I group also had significantly reduced performance on most measures of attention and executive functioning, while the bipolar II group only had a significantly reduced performance on a subset of these measures. On average, 24% of the bipolar I group had clinically significant cognitive impairment (< or =1.5 SD below the control group mean) across measures, compared with 13% of the bipolar II group.
Patients with bipolar I and bipolar II disorder in this study have different neurocognitive profiles. Bipolar I patients have more widespread cognitive dysfunction both in pattern and magnitude, and a higher proportion has clinically significant cognitive impairments compared with patients with bipolar II. This may suggest neurobiological differences between the two bipolar subgroups.
[show abstract][hide abstract] ABSTRACT: Impaired emotion perception is documented for schizophrenia, but findings have been mixed for bipolar disorder. In healthy samples females perform better than males. This study compared emotion perception in schizophrenia and bipolar disorder and investigated the effects of gender.
Visual (facial pictures) and auditory (sentences) emotional stimuli were presented for identification and discrimination in groups of participants with schizophrenia, bipolar disorder and healthy controls.
Visual emotion perception was unimpaired in both clinical groups, but the schizophrenia sample showed reduced auditory emotion perception. Healthy males and male schizophrenia subjects performed worse than their female counterparts, whereas there were no gender differences within the bipolar group.
A disease-specific auditory emotion processing deficit was confirmed in schizophrenia, especially for males. Participants with bipolar disorder performed unimpaired.