Brief summary

The aim of the study is to provide preliminary data on the relationship of Essential Fatty Acids (EFAs) to cognitive and electrophysiological measures of brain and behavioural functions in adults with attention deficit hyperactivity disorder (ADHD) and controls. This main aim will be achieved in two ways. First the investigators will measure the relationship of the various measures to blood levels of EFAs in ADHD cases and controls. Secondly, the potential effects of dietary supplementation with EFAs on cognitive-electrophysiological and behavioural measures in ADHD cases will be investigated. We will evaluate the extent to which changes in neuronal activity and cognitive performance are related to behavioural and functional measures over time. This is to be carried out by conducting a randomised controlled trial of fish oil supplementation in adults with ADHD (The OCEAN study: Oils and Cognitive Effects in Adult Neurodevelopment).

The study design will be a 6-month double blind placebo control study with a group of 80 adults with a diagnosis of ADHD. The group will be divided into 40 participants who receive EFA dietary supplements and 40 who receive placebo, over a 6-month period. Allocation to EFA dietary supplementation and placebo groups will be randomly allocated and blind to both the investigator and participants. In addition a sample of 30 controls will take part in baseline levels of assessment and be used for case-control comparisons to investigate the links between EFA blood levels and cognitive-electrophysiological function at one time point.

The study design will enable preliminary data to address the following hypotheses:

1. Changes in cognitive and electrophysiological function (neuronal activity) will be found following supplementation with dietary EFAs.
2. Changes in cognition and/or brain activity will be related to blood levels of EFAs.
3. Changes in cognitive performance and electrophysiological parameters will correlate with behavioural function, affective regulation or functional impairments.
4. At baseline, case-control differences in EFA blood-levels will be found which will be linked to cognitive and electrophysiological function.

Inclusion Criteria:

• Cases:
• Clinical diagnosis of ADHD (combined or inattentive type)
• Controls:
• Screen below threshold for ADHD

Exclusion Criteria:

• Cases:
• Autism spectrum disorder
• Recurrent major depression
• Bipolar I disorder
• Psychotic disorders
• Obsessive compulsive disorder
• Learning difficulties (IQ < 80)
• Neurological problems
• Drug abuse
• Those who are already taking EFA supplements
• Metabolic conditions
• Infectious diseases
• Controls:
• ADHD
• All other exclusion criteria for cases as above