Neuropsychology, Neuroimage and Neurophysiology in Adults With ADHD

Attention deficit/hyperactivity disorder (ADHD) is a common (3-10%), early-onset, clinically and genetically heterogeneous neuropsychiatric disorder with lifelong neuropsychological deficits. Despite extensive research in adult ADHD in western countries, there has been no published data about adult ADHD in Taiwan except the PI's and colleagues' previous works on pharmacotherapy in adults with ADHD and only few endophenotype studies based on adults with ADHD in the world. The ultimate goals of this 5-year project are to identify which neuropsychological, functional and structural connectivity, and neurophysiological variables can be effective endophenotypes (biomarkers) for ADHD based on unaffected sibling (1st-3rd years) and follow-up (4th-5th years) designs. With the accomplishment of the following study goals, this study will be the first study on the topics of neuroimaging and neurophysiological endophenotypes on adult ADHD using advanced imaging techniques (i.e., Tract-based autonomic analysis, TBAA) and comprehensive clinical and neurocognitive data. This proposal has one primary aim and four secondary aims:

Primary Aim:

• To validate structural (assessed by TBAA using diffusing spectrum imaging, DSI) and functional connectivity (assessed by resting-state fMRI) in frontostriatal, frontoparietal and other circuitries, and neurophysiological functions (assessed by stop-signal event-related potential [ERP]: N2, P3, ERN, Pe) as effective imaging endophenotypes by demonstrating the intermediate position of unaffected siblings between ADHD probands, and age-, sex-, handedness-, and IQ-matched adult neurotypical and association with DAT1 and NET (SLC6A2) variants;

Secondary Aims:

• To validate the executive functions (EF), sustained attention (SA), intraindividual variability (IIV), visual-spatial memory (VM) as effective neurocognitive endophenotypes by demonstrating the intermediate position of unaffected siblings between ADHD probands, and adult neurotypical;
• To examine the developmental trajectory and stability of neuropsychological functions and structural and functional connectivity from childhood to adolescence and young adulthood;
• To correlate the data from structural (morphometric, cortical thickness, gyrification, fiber tract integrity) and functional connectivity (rsfMRI), neuropsychology (Executive function, visual-spatial memory, sustained attention, variability), neurophysiology (Stop-signal ERP) and ADHD core symptoms stratifying by the presence of ADHD, presence of DAT1 and NET (SLC6A2) variants, proband-unaffected sibling dyads, and different developmental stages.

Inclusion criteria

• Subjects aged 16-30, who have clinical diagnosis of a ADHD according to the DSM-IV and DSM-5 diagnostic criteria, and who have never been treated with medication for ADHD treatment. At least 30 out of 60 subjects have same-sex unaffected siblings.

Exclusion criteria

• The subjects will be excluded from the study if they meet any of the following criteria: (1) Comorbidity with DSM-IV-TR or DSM-5 diagnoses of autism spectrum disorder, schizophrenia, schizoaffective disorder, delusional disorder, other psychotic disorder, organic psychosis, schizotypal personality disorder, bipolar disorder, depression, severe anxiety disorders or substance use; (2) With neurodegenerative disorder, epilepsy, involuntary movement disorder, congenital metabolic disorder, brain tumor, history of severe head trauma, and history of craniotomy; (3)With visual or hearing impairments, or motor disability which may influence the process of MRI assessment; and (4) Full-scale IQ lower than 80.