Fish Oil Affects Cognition and ADHD Symptoms in Adults With Autism Spectrum Disorder
Condition: Autism Spectrum Disorder; Attention Deficit Hyperactivity Disorder
MeSH terms: Autistic Disorder; Attention Deficit Disorder with Hyperactivity; Autism Spectrum Disorder; Child Development Disorders, Pervasive
Study type: Interventional

Summary: 
      The prevalence of autism spectrum disorder (ASD) is rising and was estimated to have a
      prevalence of around 1.5% in developed countries in 2016. ASD is characterized by impairments
      in social interaction and repetitive behavior and is associated with executive dysfunction
      such as impaired working memory, inhibition, and flexibility. Furthermore, ASD is often
      associated with multiple comorbidities such as attention-deficit/hyperactivity disorder
      (ADHD), depression, and anxiety.

      Systematic reviews and meta-analyses indicate that fish oil (FO) supplementation improves
      attention, impulsivity, and hyperactivity in children with ADHD and beneficial effects in
      adults with depression and anxiety. Some randomized trials in children with ASD have shown
      improvements on selected executive functions, but results from meta-analysis are inconsistent
      and no trial has examined the effect in adults with ASD. Furthermore, most of the previous
      studies have mainly assessed effects by questionnaires and no objective tests, only provided
      low doses (<1.5 g/d of n-3 long-chain polyunsaturated fatty acids) and none of them have
      examined the potential influence of comorbid ADHD, depression, or anxiety.

      The aim of the study was to examine the effect of FO on sustained attention and visuospatial
      short-term memory memory, as well as cognitive inhibition, executive function, and core
      symptoms of ASD, and of ADHD, and social function in adults with ASD. In light of the shared
      and additive cognitive impairments in individuals with both ASD and ADHD, the hypothesis was
      that individuals with comorbid ADHD will show the most pronounced effects. The study
      furthermore aimed to examine potential interaction with depression, anxiety, and gender.

      This was investigated in a randomized double-blind head-to-tail crossover trial in 26 adults
      with ASD, who are provided with FO and safflower oil (SO) for 4 weeks each. The subjects were
      examined at baseline and after each period with tests of attention and working memory
      (primary endpoints) as well as a test of cognitive flexibility and clinical questionnaires.
    

Detailed description: 
      The aim of the study was to examine the effect of fish oil (FO) on sustained attention and
      visuospatial short-term memory memory, as well as cognitive inhibition, executive function,
      and core symptoms of ASD, and of ADHD, and social function in adults with ASD. In light of
      the shared and additive cognitive impairments in individuals with both ASD and ADHD, the
      hypothesis was that individuals with comorbid ADHD will show the most pronounced effects. The
      study furthermore aimed to examine potential interaction with depression, anxiety, and
      gender.

      This was investigated in a 2 × 4 week randomized double-blind head-to-tail crossover study
      with FO and safflower oil (SO).

      Participants were recruited by advertisements posted in autism-related institutions and
      autism forums on Facebook as well as via personal networking. The study aimed to recruit up
      to thirty participants and ended up with twenty six participants.

      The intervention in the two periods consisted of four capsules two times per day of FO
      (corresponding to approximately 5,2 g/d long-chain polyunsaturated fatty acids) and SO (1.2
      g/day of linoleic acid), respectively. The intervention sequences: FO → SO or SO → FO was
      determined by a randomization list generated by a person, who was not involved in the data
      collection and FO and SO capsules were packed in white containers of similar appearance in
      the same known excess amount of what was required for four weeks. The participants were
      allotted to one of the intervention sequences by ID numbers based on date and time of their
      first visit and were provided with the appropriate pre-ID labelled container in the beginning
      of each period.

      The participants were examined at baseline and after each period. The assessment consisted of
      the following: attention (The d2 Test of Attention) and spatial working memory (Corsi
      Block-Tapping Test) as primary outcomes and as secondary outcomes, inhibition and flexibility
      (The Stroop Word-Color Test), ADHD symptoms (Conners Rating Scale), and executive and social
      functions assessed by the Behavioral Inventory of Executive Function and Social
      Responsiveness Scale, respectively. Compliance was verified by whole-blood fatty acid
      analysis.
    

Intervention name(s): Experimental: Fish Oil; Comparator: Safflower Oil
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Participants are provided with fish oil capsules and asked to take 4 capsules of 1000 mg twice a day (in total 5.2 mg/day of long-chain n-3 fatty acids hereof 2400 mg of eicosapentaenoic acid and 1600 mg of docosahexaenoic acid) for 4 weeks.; Participants are provided with fish oil capsules and asked to take 4 capsules of 500 mg twice a day (containing ~ 3000 mg of linoleic acid) for 4 weeks.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized 2 x 4 weeks head-to-tail crossover trial.
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science