Fish Oil Affects Cognition and ADHD Symptoms in Adults With Autism Spectrum Disorder

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.