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ORIGINAL PAPER
Parents’ and Child Health Professionals’ Attitudes
Towards Dietary Interventions for Children with Autism
Spectrum Disorders
Elizabeth Winburn
•
Jenna Charlton
•
Helen McConachie
•
Elaine McColl
•
Jeremy Parr
•
Anne O’Hare
•
Gillian Baird
•
Paul Gringras
•
David C. Wilson
•
Ashley Adamson
•
Sandra Adams
•
Ann Le Couteur
Published online: 1 September 2013
Ó Springer Science+Business Media New York 2013
Abstract Parents of children with autism spectrum dis-
orders (ASD) use a wide range of interventions including
poorly evidenced dietary interventions. To investigate
parents’ and professionals’ experience of dietary inter-
ventions and attitudes towards a proposed trial to evaluate
the gluten free casein free diet (GFCFD). Survey of UK
parents of children with ASD, and professionals. 258 par-
ents and 244 professionals participated. 83 % of children
had received a range of dietary manipulations; three
quarters of professionals have been asked for advice about
GFCFD. Respondents identified an inadequate evidence
base for dietary interventions in ASD and suggested
modifications to a proposed trial design. Both parents and
professionals supported the need for further evaluation of
dietary interventions in ASD.
Keywords Autism ASD Dietary interventions
Gluten Casein
Introduction
Recent ASD studies have reported a prevalence of at least 1 %
of the child population (Baird et al. 2006; Kogan et al. 2009).
Although there is no cure for ASD, there is general agreement
that early diagnosis and access to appropriate therapeutic
interventions may improve outcome (Dawson et al. 2010;
Green et al. 2010;Reaven2011; Volkmar et al. 2004). A variety
of interventions have been proposed but there is little evidence
to inform parents and professionals about which intervention or
combination of interventions might benefit an individual child
at any particular time (Carter et al. 2011a;Lordetal.2006;
Ospina et al. 2008). Many interventions are time consuming
and costly with little information about their efficacy, effec-
tiveness or their potential to do harm. Parents report a lack of
advice from professionals about which interventions to choose,
E. Winburn
Solent NHS Trust, Southampton SO16 9QX, UK
J. Charlton
Communication and Language Sciences, Newcastle University,
Newcastle upon Tyne, UK
H. McConachie A. Le Couteur (& )
Institute of Health and Society, Sir James Spence Institute,
Newcastle University, 3rd Floor, Royal Victoria Infirmary,
Newcastle upon Tyne NE1 4LP, UK
e-mail: a.s.le-couteur@newcastle.ac.uk
E. McColl
Newcastle Clinical Trials Unit, The Medical School, Newcastle
University, Newcastle upon Tyne NE2 4HH, UK
J. Parr
Institute of Neuroscience, Newcastle University, Newcastle upon
Tyne, UK
A. O’Hare D. C. Wilson
Child Life and Health, University of Edinburgh, Edinburgh
EH9 1UW, Scotland, UK
G. Baird P. Gringras
Guys and Thomas’ NHS Foundation Trust, London SE1 7EH,
UK
A. Adamson
Institute of Health & Society and Human Nutrition Research
Centre, Newcastle University, Newcastle upon Tyne NE2 4HH,
UK
S. Adams
Department of Nutrition and Dietetics, North Tyneside General
Hospital, North Shields, UK
123
J Autism Dev Disord (2014) 44:747–757
DOI 10.1007/s10803-013-1922-8
and look to alternative sources for information: usually other
parents, the media and the internet (Mackintosh et al. 2005).
The US Interagency Autism Coordinating Committee
(IACC) Strategic Plan has called for a balance between
rigorous evaluation of existing interventions (large-scale
randomized controlled trials, including comparative stud-
ies) and research into novel, targeted treatments (Inter-
agency Autism Coordinating Committee 2010). In the UK,
the need to support autism intervention research has been
identified as a key priority, with both researchers and
parents agreeing that dietary interventions should be a
particular research focus (Charman and Clare 2004; Med-
ical Research Council 2001; Rutter 2011).
Despite the lack of evidence, parents understandably
pursue a range of different types of interventions. Several
recent surveys have identified that on average children are
receiving between four and six interventions, with younger
children more likely to be using dietary and behavioral/
educational/alternative interventions, and pharmacological
interventions being more widely used for adolescents
(Green et al. 2006; Carter et al. 2011b; Goin-Kochel et al.
2007). Dietary interventions, such as restrictive diets and
dietary supplements are used, with many parents falsely
believing that such interventions are likely to be free of
adverse effects, and safer than medications (Goin-Kochel
et al. 2007; Hanson et al. 2007). However the use of
restrictive diets is likely to pose additional risks for chil-
dren with ASD who may already have feeding problems
including a ‘self-imposed’ restrictive diet. Previous studies
have found that children with ASD have more amino acid
deficiencies and lower bone density than age matched
controls, and in these studies there was a greater problem in
those children on restricted diets (Arnold et al. 2003;
Hediger et al. 2008; Keen 2008). However although several
authors have reported that children with ASD have more
restricted diets than age matched controls without ASD
(Ahearn et al. 2001; Keen 2008), a recent general popu-
lation study (using the Avon Longitudinal sample—AL-
SPAC sample) reported no differences in energy intake or
growth for children with ASD (Emond et al. 2010). A
further study compared food records and body mass index
(BMI) of children with ASD aged 2–11 with matched
controls (Hyman et al. 2012). No differences in nutritional
intake were found between groups, but children with ASD
were more likely to be overweight in the aged 2–5 group,
and underweight in the aged 5–11 group.
The most commonly used restrictive dietary intervention
is the gluten free casein free diet (GFCFD; Elder 2008;
Carter et al. 2011b). This diet can place a substantial bur-
den on families, and has considerable resource implications
for healthcare services (Bowers 2002; Parr 2010). Parental
reports make claims for high rates of success using the
GFCFD as an intervention in ASD. For example (Goin-
Kochel et al. 2009), reported that 51 % of parents said that
their children improved while on the GFCFD. However in
their online survey it was difficult to know how parents
attributed their efficacy ratings to individual treatments
since most of the children were receiving multiple treat-
ments. Further since parents used the same Likert-like four
point rating for each intervention, it was not possible to
identify what specific behavioral outcomes parents saw as
changed. (Goin-Kochel et al. 2007).
There have been a number of small scale exploratory
studies of the effectiveness of the GFCFD (Knivsberg et al.
2002; Elder et al. 2006; Johnson et al.
2011). Knivsberg
et al. (2002) was a small (10 subjects per group) single
blind Randomised Controlled Trial of the GFCFD imple-
mented by parents for 12 months. Subjects were selected if
they had a diagnosis of autism and urinary peptide abnor-
malities (believed to reflect incomplete breakdown of gli-
adin, gluten and casein). The diet intervention group
showed significant improvements in ‘autistic traits’ as
reported from parent interviews. Compliance with the diet
was not measured. Elder et al. (2006) was a pilot study of
GFCFD for 6 weeks in a heterogeneous sample that
reported no effect. Johnson et al. (2011)reported a 3-month,
open label, randomised, parallel group design using the
GFCFD and a healthy, low sugar diet thus controlling for
the increased time and attention that is required to imple-
ment a diet such as the GFCFD. No significant differences
were noted between the groups but the authors questioned
whether the GFCFD might need to be implemented for a
longer period of time before gains can be observed. No
significant nutritional differences or side effects were
reported but the authors identified that adherence to the
GFCFD was difficult. The largest study to date used a
single blind, non-placebo controlled design, involved 72
children, and found improvements in core autism symp-
tomatology for those using the GFCFD (Whiteley et al.
2010). Initially in the first 12 months there was a placebo
control, however all participants were assigned to GFCFD
in the second phase of the trial. In the first phase 21 %
withdrew from the study. Reasons for withdrawal included
lack of time to support the GFCFD, children not wanting to
be on the diet or no reported intervention effect. In the
second 12 month phase when all children were offered the
GFCFD more than a third of the remaining sample with-
drew (Whiteley et al. 2010).
There is no plausible biological mechanism for the
GFCFD. The ‘opioid-excess theory’ proposed that some
individuals cannot digest gluten and casein leading to the
absorption of excess peptides into the blood and then the
brain, resulting in a range of autistic behaviours. An
abnormal urinary pattern of proteins has also been reported
(Panksepp et al. 1979; Reichelt et al. 1981; Shattock et al.
1990; Whiteley et al. 1999), but these findings have not
748 J Autism Dev Disord (2014) 44:747–757
123
replicated by independent groups (Alcorn et al. 2004; Cass
et al. 2008; D’Eufemia et al. 1996; Horvath and Perman
2002; Le Couteur et al. 1988; van Elburg et al. 1995).
As there has been no large-scale randomized controlled
trial of the GFCFD, its effectiveness remains unknown
(Millward et al. 2008). We report the findings of a UK
online survey designed to investigate current attitudes to
dietary interventions, and potential support for a proposed
design for a randomized controlled trial (RCT) of the
GFCFD in young children with ASD.
Methods
Sample Size Estimation
We aimed to survey 246 UK parents of children with an
ASD and 246 UK child health professionals working with
children with ASD. The sample size was calculated to
allow us to report with 95 % confidence the ‘true’ rate of
agreement in the underlying population, to within ±5%,
for survey findings/statements with approximately an 80 %
rate of agreement in our sample www.berrie.dds.nl/calcss.
htm (Woodall et al. 2010).
The study received approval from a UK research ethics
committee and the local (Northumberland, Tyne and Wear)
NHS Trust.
Participants
To achieve the recruitment targets and gain a broad range
of views, pediatricians, pediatric neurologists, pediatric
gastroenterologists, child psychiatrists and pediatric dieti-
tians were contacted. The aim was to recruit UK-wide.
Through the relevant National Royal Colleges, professional
bodies, national professional newsletters and UK multi-
disciplinary Child Development Centers email or postal
invitations to participate in the study were sent to the
majority of relevant professionals. Parents were recruited
through two regional databases, online parent support fora
and national parent support organizations.
Materials
Two versions of a survey questionnaire (parent and pro-
fessional) were designed and piloted. Questionnaire
development was undertaken in consultation with parents
and child health professionals. Most questions required
fixed-choice responses, though for some items there was
the facility for brief free-text responses. The questionnaire
was presented in four sections: demographic characteris-
tics; experience and use of interventions for treatment of
ASD in young children; research priorities; and a final
section contained a summary description (‘vignette’) of the
design for a proposed double-blind, multi-site randomized
controlled trial (RCT) to evaluate the impact of GFCFD in
young pre-school children with ASD together with an
illustrative flow chart (see ‘‘Appendix’’).
The vignette included an explanation of the need for
randomization and the procedures for access to proposed
levels of additional professional support (dietitian and
pediatrician). The vignette also included a description of
‘Test Foods’ (two versions of food products such as bis-
cuits, muffins or porridge), manufactured to be either
GFCF or containing precise quantities of gluten and casein)
that would be included in the children’s diet for the dura-
tion of the RCT, so that all parents and researchers
remained ‘blind’ to the introduction of gluten and casein to
half the children in the trial. Once survey participants had
read the vignette and flowchart, they were asked a series of
questions with fixed-choice responses (with space for brief
free text comments) to ascertain opinions about the pro-
posed trial design and levels of clinical support. This sec-
tion of the questionnaire was devised to investigate
possible barriers and facilitators to recruitment and reten-
tion of families within the proposed research design. Other
details about the trial (such as the inclusion/exclusion cri-
teria and safety plan) were not included, in order to keep
the vignette brief.
Paper forms of the survey questionnaires were available
for respondents who did not have web access or expressed
a preference for a paper version (Copies of the question-
naires are available from the corresponding author on
request).
Procedure
The study took place over 10 months between April 2009
and February 2010. Participants initially accessed the
Newcastle University PADIA (Parents’ and Professionals’
Attitudes towards Dietary Intervention in Autism) research
website (http://research.ncl.ac.uk/cargo-ne/PADIA.html)to
express their interest in the survey, completed a short series
of questions regarding their status (parent or professional),
email address, postcode (zip code) and source from which
they heard about the study. Each participant was allocated
a unique identification (ID) number to access an informa-
tion sheet and consent form before completing the full
survey anonymously. All respondents were given the
opportunity to enter a free prize draw to win a laptop
(separate draws for parents and professionals). The two
stage recruitment procedure was used to ensure collection
of consent and socio-demographic information, protect
confidentiality and reduce risk of repeated responses.
Once a unique ID had been allocated, if the question-
naire had not been completed, automatic reminders were
J Autism Dev Disord (2014) 44:747–757 749
123
sent to the associated email address at 2 and 4 weeks after
registration (Edwards et al. 2007; McColl et al. 2001).
All survey responses were transferred to SPPS 15.0 for
Windows software package for analysis. Descriptive sta-
tistics were used to summarize the experiences and atti-
tudes of parents and professionals.
Results
Sample Composition
Two hundred and fifty eight of 361 (71 %) parents and 244
of 317 (77 %) professionals who expressed an interest
completed relevant versions of the questionnaires. 41 %
(105) of parents were recruited from two regional dat-
abases (North East England and Edinburgh Scotland).
80 % of parents and 89 % of professionals completed the
survey online, with the remainder using a paper copy.
Completeness of the data set for individual questions ran-
ged from 90.3 to 99.6 % (parents) and from 86.8 to 100 %
(professionals). For descriptive statistics the denominator
was adjusted for individual questions as necessary.
Most parents who completed the survey were white
British birth mothers of a child with an ASD (75 %). 80 % of
mothers were homeowners and over half were employed
(54 %) and educated to degree level (57 %). Child charac-
teristics are detailed in Table 1. 65 % of parents reported that
their child experienced three or more problem behaviors per
week. There was no significant relationship between age of
child and frequency of problem behaviors. The most frequent
behaviors were selective eating (51 %), sensory reactions
(52 %) together with temper tantrums (41 %), hyperactivity
(40 %) and sleep problems (40 %). These rates of parent
reported child problem behaviors are similar to a UK rep-
resentative database sample (Maskey et al. 2012).
Considering professionals who completed the survey,
42 % were Pediatricians (including 10 % Pediatric Neu-
rodisability Specialists), 32 % Child and Adolescent Psy-
chiatrists, 17 % Dietitians and 9 % Psychologists.
ASD Intervention Use
Parents reported (from a list of 21 possible interventions)
that they were currently implementing a median of four
interventions (range 0–15) with their child. Current inter-
vention type and rates are detailed in Fig. 1. The use of
speech/communication, and educational interventions and
some form of dietary manipulation were all reported by
over 80 % of parents. Dietary manipulation included use of
special diets such as the GFCFD and dietary supplements
(these were grouped as a single category within the fixed
response format, with the descriptor ‘micronutrients, vita-
mins, minerals, fish oils).
Although 75 % of professionals reported that they had
been approached by families for information about the
GFCFD, most (the majority of whom were Child and
Adolescent Psychiatrists) estimated that fewer than 10 %
of the children with ASD on their current caseload were
using the GFCFD. However 26 % of professionals (mostly
Pediatric Dietitians and Pediatricians) reported that
10–20 % of the children with ASD they see are using the
GFCFD. A smaller number of Pediatric Neurodisability
specialists and Child and Adolescent Psychiatrists reported
that at least 20 % of their ASD caseload were on the
GFCFD.
Table 1 Child characteristics (n = 258)
Child characteristic % (n =)
Gender
Male:female 84.16 (216:42) (ratio 4:1)
Age at survey completion
\2 years 11 months 2 (5)
3–5 years 11 months 31 (81)
6–11 years 67 (172)
ASD diagnosis
Autism 27 (70)
Asperger’s syndrome 20 (52)
Autism spectrum disorder 49 (127)
PDD-NOS/atypical autism 4 (9)
Age at diagnosis
\2 years 11 months 27 (70)
3–5 years 11 months 57 (146)
6–11 years 16 (42)
Language level
No meaningful speech 19 (50)
Single words and phrases 28 (70)
Sentences with good grammar 51 (132)
Other (no details) 1 (5)
Learning disability 31 (81)
Type of educational establishment attended
Mainstream (school, nursery, unit
attached)
71 (179)
Specialist provision 28 (70)
Home ed. 2 (4)
Educational support
Individual education plan
a
57 (150)
Statement of special educational needs
b
55 (144)
a
An Individual Education Plan (IEP) is a teaching and learning plan
devised to identify the targets, provision and outcomes for a child
identified with special educational needs
b
Statement of Special Educational Needs is a legal document issued
by the Local Authority responsible for education, following an in-
depth multidisciplinary assessment of the child’s needs
750 J Autism Dev Disord (2014) 44:747–757
123
Attitudes Towards Dietary Interventions
Eighty three percent of parents had tried a range of dietary
manipulations (including any special diet and use of dietary
supplements) with their child. 35 % were currently using a
special diet and 46 % were currently using dietary sup-
plements. There was no significant relationship between
age of child and rate of dietary intervention use. The
majority (86 %) of parents were aware of the GFCFD and
29 % were currently implementing it. For the small number
of parents implementing other diets, there was no consis-
tent pattern discernable from the few free-text descriptors
provided by parents (examples included the CHO (carbo-
hydrate) diet and soya diet).
For the 76 children currently on the GFCFD, most
parents reported a change in their child’s behavior with
‘significant improvements’ (5 point scale: significant
decline, decline, no change, improvement, significant
improvement) most frequently reported for gastrointestinal
symptoms (54 %). Other symptoms reported to ‘signifi-
cantly improve’ included concentration and attention
(42 %), communication (29 %), social interaction (25 %)
and repetitive interests and behaviors (20 %). A further 22
parents (29 % of children on the GFCFD) reported ‘some
improvement’ in gastrointestinal symptoms. Thus the
majority of children (83 %, n = 63) on the GFCFD
experienced at least some improvement in gastrointestinal
symptoms. Only 8 of these 63 children had no reported
change in social interaction and 13 had no reported change
in communication. A higher figure of 20 children were
reported to show no change in repetitive interests and
behaviors.
For 10 children there was worsening anxiety and
aggression (Table 2).
Seventy three percent of professionals stated that there
was ‘insufficient evidence about the benefits or otherwise’
of the GFCFD. Nearly two thirds of professionals felt that
they had sufficient knowledge about the GFCFD to discuss
it with families. Most reported that they would support
families wishing to pursue the GFCFD but would not
specifically recommend it to families. 19 % stated that they
would advise parents against the use of the GFCFD.
Research Priorities
Parents and professionals were asked to rate their top 3
priorities from a list of 22 ASD research topics. The option
topics were based on previous surveys (Charman and Clare
2004; Mills and Wing 2005) and findings from consultation
with parents and professionals during the questionnaire
development. 16 % (the second largest grouping) of pro-
fessionals and just under 10 % of parents (by fourth largest
group of parents) rated dietary interventions and behavioral
difficulties as their top priority for ASD research (data
Fig. 1 Interventions currently
used by parents. Single asterisk
Dietary manipulations included
use of special diets such as the
GFCFD and dietary
supplements (micronutrients,
vitamins, minerals, fish oils).
Double asterisk complementary
and Alternative Therapies
included homeopathy,
acupuncture and massage
Table 2 Parent reports of
current use of dietary
interventions (special diets and
supplements)
Age Dietary
Supplement
%(n)
Special Diet
%(n)
GFCF Diet
%(n)
3 or more behaviour
problems
%(n)
\2 year 11 months 40 (2) 20 (1) 20 (1) 40 (2)
3–5 year–11 months 41 (33) 37 (30) 31 (25) 66 (54)
6–11 years 50 (86) 34 (59) 29 (50) 67 (115)
Total 47 (121) 35 (90) 29 (76) 66 (171)
J Autism Dev Disord (2014) 44:747–757 751
123
available from last author). Parents with children under the
age of 3 (only 5 children) prioritized research into causes
and early intervention; aged 3–5 years 11 months—com-
munication, causes, early intervention, behavior difficulties
and dietary interventions. For children aged 6 years–
11 years, parents were most interested in research into
causes, communication, dietary interventions and behavior
difficulties. For children talking in sentences, parents rated
causes, behavioral difficulties, communication, early
intervention, dietary interventions and anxiety as their top
priorities.
Professionals top 5 research priorities were: behavioral
difficulties (17 %), dietary interventions (16 %), causes
(14 %), early intervention (just under 12 %) and diagnosis
(8 %) (further details available from last author).
Barriers and Facilitators Towards Participation
in a Proposed Randomized Controlled Trial
of the GFCFD
Seventy eight percent of parents reported they would
consider taking part in the proposed RCT. Of these, the
majority 109 (85 %) answered ‘yes’ and a further 13
(10 %) ‘maybe’ when asked if they would be prepared for
their child to be randomly allocated to a ‘Test Food group
with a 50 % chance of being in the gluten and casein free
group’. Of the parents who suggested they would ‘agree’
to take part, nearly half (45 %) answered a subsequent
item by scoring that ‘yes’ they would be more likely to
do so if they were not ‘blind’ to group allocation. For
parents who would not take part, most (63 %) would be
no more likely to take part if they were not blind. to
group allocation.
Parents were more likely to agree to take part if they
were not currently implementing the GFCFD for their child
(v
2
= 11.670, df = 2, p = \0.01). Of the 60 parents who
had previously taken part in an autism research project,
most responded positively to considering the proposed trial
but 19 who had taken part in previous research, indicated
they would definitely not take part (v
2
= 7.287, df = 2,
p = 0.026). All these parents expressed concerns about the
proposed study—citing for example concerns about the
impact of the research on their child’s existing limited diet,
or that their child was already on the GFCFD and they
would be reluctant to discontinue this intervention.
Considering the trial protocol, 77 % of parents thought
there was sufficient dietitian support and this was signifi-
cantly associated with likelihood to take part (v
2
= 30.539,
df = 2, p \ 0.001). Despite this, when asked what might
be the most difficult part of the study, 44 % of parents
expressed concern about getting their child to eat the range
of ‘Test’ foods that would be included in the child’s diet for
the duration of the trial to maintain blinding.
Professionals’ Views
Seventy five percent of professionals reported that they
would be prepared to recruit children to the proposed
GFCFD trial. Just under one third (31 %) had previously
referred families to ASD research studies. Professionals
highlighted a need for parents to have reliable access to
dietitians (telephone and face-to-face). Perceived barriers
to participation included that ‘the child’s diet may be too
limited to take part in the trial, and whether families would
be able to follow the procedure for the duration of the trial
(i.e. 6 months).
Discussion
This study has identified that most parents of children with
ASD who responded to this UK survey use a variety of
interventions (most frequently speech/communication,
educational and a mixture of dietary manipulations) and are
usually implementing several interventions at the same
time. These findings are in keeping with other recent sur-
veys of parents of children with ASD conducted in US and
Australia and highlight the multimodal approaches adopted
by parents as they combine different types of interventions
for their children (Carter et al. 2011b; Goin-Kochel et al.
2007; Green et al. 2006). The majority of respondents
(parents and professionals) were aware of the GFCFD and
indeed many parents had considered and/or tried the
GFCFD. The most popular dietary manipulations (again
often used in combination) were a range of dietary sup-
plements and use of special diets (usually the GFCFD). The
number of parents who reported that they were currently
implementing the GFCFD was at the higher end of previ-
ously reported surveys (Levy and Hyman 2003; Perrin
et al. 2012).
When parents were asked to specify the observed effects
of the GFCFD, in line with other surveys, they reported
improvement across a wide range of behaviors. Most par-
ents reported at least some improvement in gastrointestinal
symptoms often in combination with other behaviors.
Some parents reported significant improvements in other
behaviors (including concentration, attention and less fre-
quently in some of the core ASD behaviors). The parents’
preference for combinations of dietary manipulations, and
the lack of specificity in reported improved behaviors (but
usually including GI symptoms); add complexity to deci-
sions about appropriate research design and choice of pri-
mary outcome measure(s) for evaluation of the impact of a
complex intervention such as the GFCFD as an interven-
tion for ASD.
There was general agreement from both parent and
professional respondents for the need for more information
752 J Autism Dev Disord (2014) 44:747–757
123
about, and for more research on, a range of interventions
including dietary supplements and the use of ‘special’
diets. Professionals considered that they had sufficient
knowledge to discuss the GFCFD with parents who are
considering implementing the diet. These discussions may
well include issues such as the lack of a robust evidence
base for the GFCFD (Isherwood et al. 2011).
Dietary interventions were not the number one priority
for the majority of parents, but for parents with children of
different ages it was in the top 4–5 research topics. For
professionals, research into dietary intervention was the
second highest rated research priority. Many professionals
also indicated that they would appreciate further training in
dietary and other biomedical interventions. Since all pro-
fessionals who participated in this study indicated that they
saw a varying number of children with ASD whose parents
were considering and/or implementing the GFCFD, this
training would be relevant to all professional groups.
Indeed in the light of the professionals’ reported experience
(irrespective of their discipline), all professional groups do
need to be aware that at any one time at least some families
on their caseload may be contemplating/implementing the
GFCFD.
These findings may reflect the bias of those who com-
pleted the survey but, in keeping with previous research
recommendations (Medical Research Council 2001), it also
suggests that the dilemma of whether or not to attempt to
implement dietary interventions (such as the GFCFD) in
the absence of a robust evidence base continues to be a
relevant topic for both research and current clinical prac-
tice, with the inevitable resource implications for affected
families, research funding and service providers.
The novel use of a vignette protocol and flow chart to
illustrate the proposed design for an RCT within the survey
format appeared to be a successful way of investigating
attitudes to and identifying potential facilitators and bar-
riers for, a proposed trial to investigate the impact of the
GFCFD in young children with ASD. Respondents were
able to complete the sections of the questionnaire dedicated
to the proposed trial design. Over three-quarters of parents
and professionals stated their preparedness to be involved
in a proposed RCT of the GFCFD and provided valuable
feedback in response to structured questions about the trial
design. This reported willingness of both parents and
practitioners to engage in robustly designed research to
investigate a ‘controversial’ dietary intervention, where
there is a lack of scientific evidence, is encouraging for
potential researchers and grant funding organizations.
However, for an intervention such as the GFCFD, what is
the likelihood that funding one or more fully powered
RCTs will alter patterns of demand and uptake for the
intervention? An example of another ‘controversial’ bio-
medical but non-dietary intervention previously reported as
a treatment for ASD was the use of secretin (a gastroin-
testinal hormone). Following the publication of a series of
RCTs that reported an important and significant placebo
effect, but a lack of response to secretin, there has been a
consistent decline in and now virtual absence of parents’
requests for this hormone as a treatment for ASD (Sandler
2005; Williams et al. 2005).
From the parents’ and professionals’ responses, three
factors (current use of GFCFD, previous experience of
research and level of professional support) were identified
as potential barriers to recruitment and retention for the
proposed trial.
For some parents currently implementing the GFCFD it
might be that if they have already identified that their child is
benefitting or hope that there will be benefit from the
GFCFD, they may not want to risk allocation to the control
group. However for the majority of the parents neither pre-
vious use of the GFCFD nor the consideration of future
implementation of the GFCFD appeared to affect potential
for successful recruitment. Further consideration is needed
to clarify for parents who may be particularly committed to
this intervention, what might be the circumstances in which
they would be prepared to support the evaluation of the
GFCFD in their own child and in the wider ASD population.
There was a small subgroup of parents with prior
experience of taking part in research who were not pre-
pared for their child to take part in this proposed trial. All
gave reasons related to their child’s diet and/or other
constraints about the study—such as that their child was
already on the GFCFD and they would be reluctant to
discontinue this intervention. No parents cited their previ-
ous experience of research as a barrier to taking part.
However understanding service user attitudes to research,
their knowledge of research methodologies and minimizing
any potential longer term adverse impact of taking part in
research are important considerations. Linked to this con-
sideration of participants’ knowledge and understanding of
research design is another intriguing and unexpected result
that, amongst the parents who agreed that they would be
prepared to take part in the proposed RCT, 45 % also
indicated that they would be more likely to take part if they
were not ‘blind’ to group allocation. Whether this finding
indicated a lack of understanding about the proposed
research design, ambivalence about randomization or an
ambiguity in the design of the question is unclear. This
finding highlights the importance of detailed explanation
and a probable need for ongoing discussion to maximise
understanding at time of recruitment and to support com-
pliance and retention of participants. In the UK organiza-
tions such as INVOLVE funded by the National Institute
for Health Research promote knowledge and learning on
public engagement, partnership and involvement in
research (INVOLVE 2010).
J Autism Dev Disord (2014) 44:747–757 753
123
Parents agreed that the proposed levels of professional
support within the trial design presented would be suffi-
cient, but in common with the professionals they were
concerned about following the diet protocol for 6 months.
Consideration of reducing the duration of the GFCFD
protocol to 3 months might have been more acceptable to
parents and professionals but other authors have queried
whether this would then be a sufficient duration to detect a
beneficial effect (Johnson et al. 2011). Professionals rec-
ommended the need for additional professional support in
the form of ‘reliable’ telephone access with the dietitian.
This would allow parents to access urgent advice in addi-
tion to planned appointments with professionals. However
professionals also had specific concerns about the risks of
including children with very restricted diets (despite the
proposed funded availability of additional professional
support). A small feasibility study has already been
undertaken by our multisite collaboration which has dem-
onstrated that young children with ASD are prepared to eat
the Test Foods products (Adams et al. 2008).
Understanding the barriers and facilitators that impact
on recruitment and retention to evaluation studies is
important to the successful outcome of intervention
research (Friedman et al. 2010; Woodall et al. 2010). Most
of the factors identified in this study appear specific to the
complexity of research involving young children with
ASD. This information will be useful for refining the
research design and protocol for the evaluation of complex
interventions such as the GFCFD and other ASD inter-
ventions for which there is no firm evidence base.
The survey had a number of limitations, and also
strengths. The survey has a large sample of parents and
professionals. A two stage recruitment procedure was used
to allow collection of information about respondent char-
acteristics and minimize risk of multiple responses. These
strategies were successful—there was no evidence of sys-
tematic reporting bias from any particular group. Although
inevitably the survey respondents are likely to be those
parents and professionals with a particular interest in this
topic, parents reported a range of experiences with respect
to the GFCFD and professionals also expressed a spread of
opinions from those who wanted more information about
dietary interventions through to a smaller number who
would actively discourage parents from attempting to
implement the GFCFD. This allows us to have confidence
in the reported findings.
As with other internet surveys, parent respondents had
higher educational qualifications and were predominantly
from higher socio-economic groups. The child character-
istics were in keeping with other surveys of early years and
primary school aged children, with just under half having a
diagnosis of ASD, and most also reported to have a range
of additional problems. In this survey the majority of
children were attending mainstream educational provision
a consequence of UK education inclusion policy for chil-
dren with special needs to attend mainstream schools.
Professionals were distributed across the professional
groups which in turn reflects current UK clinical practice
(Bowers 2002; Scottish Intercollegiate Guidelines Network
2009; National Institute for Health and Clinical Excellence
2010).
Less than half the parents (41 %) were recruited from
the two regional databases but, as with previous electronic
survey studies, fathers, unemployed parents and those with
low educational attainment and low incomes were under-
represented. Further the two stage recruitment process was
a more time consuming process and almost certainly con-
tributed to the study attrition. Just over a quarter of parents
(29 %) and just under a quarter (23 %) of professionals
who registered on the PADIA website did not then use their
allocated unique ID number to access and complete the
questionnaires, despite up to two reminders. However no
systematic bias was identified between the respondents
who completed the whole process and those that only
registered an expression of interest. The predominantly
fixed-choice response format of the questionnaire limited
the amount of detailed information obtained from indi-
vidual respondents, for example little detail was obtained
about the range of dietary supplements given to children.
Conclusion
Despite lack of evidence, most parents of children with
ASD continue to implement several interventions at the
same time. Parents of children with ASD, and the profes-
sionals who work in this area, strongly endorse the need for
accurate information about a variety of interventions and
would be prepared to consider taking part in a proposed
RCT design to evaluate the GFCFD. The information
provided by the respondents will be used to improve future
research proposals with the aim to increase the scientific
evidence in this controversial area.
Acknowledgments The authors wish to thank all the parents and
professionals who took the time completing the survey and Rachael
Taylor for administrative assistance. The study was funded by Autism
Speaks.
Conflict of interest The authors declare that they have no conflicts
of interest.
754 J Autism Dev Disord (2014) 44:747–757
123
Appendix
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