Brain Connectivity in Attention Deficit Hyperactivity Disorder (ADHD)

Brain Connectivity in Attention Deficit Hyperactivity Disorder (ADHD): a Biomarker to Predict Treatment Response

This study investigates whether a relationship exists between pre-treatment brain characteristics and treatment response in adults with Attention Deficit Hyperactivity Disorder (ADHD).

There is a pressing need in psychiatry to offer more individualised treatments, and to improve outcomes from clinical trials. This 'individualised medicine' approach requires the development of biomarkers of treatment response.

60 adults with ADHD are recruited from the Adult ADHD Clinic at the Maudsley Hospital, London, United Kingdom.

The study is developed over three sessions, two at baseline (DAY 1 and DAY 2) and one after two months of treatment (follow-up).

The first two sessions are conceived as a single-blind non-randomised placebo-controlled cross-over experiment. The first 30 participants enrolled in the study receive a placebo tablet (ascorbic acid 50 mgs) on DAY 1 before the behavioural assessment and magnetic resonance imaging (MRI) scan. The behavioural assessment and the functional MRI measurements are repeated two days after (DAY 2), under a clinically effective dose (20 mgs) of short-acting methylphenidate (MPH).

The order of the tablets is reverted for the remaining 30 participants to balance any potential expectation and practice effect between the two conditions. Placebo and medication are over-encapsulated with the same red opaque capsules by the pharmacy team. Also, the protocol followed during the two sessions is absolutely identical in respect of timing and tests administered in order to keep the participants blind to the drug condition (medication or placebo).

After the scanning sessions, all the participants receive the same prescription of a long-acting formulation of MPH, according to the clinical guidelines adopted by the Maudsley Hospital. Treatment response is evaluated clinically and behaviourally after 2 months of treatment (follow-up). Pre-treatment brain characteristics are tested as potential predictors (biomarkers) of treatment response.

Inclusion Criteria:

• males
• aged 18-45 years old
• intelligent quotient (IQ) > 70 (as measured by WASI)
• diagnosis of ADHD confirmed through clinical assessment (Adult ADHD Clinic)
• non-medicated (stimulant medication-naive or not taking stimulant medication for at least 4 weeks)

Exclusion Criteria:

• no other brain disorders other than ADHD
• no condition precluding MRI scanning (e.g., metallic implants, claustrophobia)