NEUROPSYCHOLOGICAL ENDOPHENOTYPES IN ADHD: NEUROCOGNITIVE DEFICITS IN ADHD PATIENTS AND THEIR PARENTS

Objectives: Attention-deficit/hyperactivity disorder (ADHD) is a common neuropsychiatry disorder that affects 3% to 5% of school aged children. First-degree relatives of a child appear to be at a 4.6-fold to 7.6-fold higher morbidity risk for ADHD than relatives of normal controls. The objective of research was to evaluate the presence of common neurocognitive traits in parents of ADHD patients and their children.

Methods: 20 boys with combined ADHD and 25 controls were evaluated. 40 parents were compared to 40 controls matched for age and sex. All subjects performed a clinical-psychopathological and a neuropsychological battery. The children and controls were evaluated with K-SADS-PL, Conners Parent Rating Scale, Conners Parent Rating Scale, SNAP-IV. The parents and controls were examined with SCID I, Adult ADHD Self Report Scale (ASRS) and Wender Utah Rating Scales (WURS). Five main domains of executive functions and attention were studied in all subjects with WCST, ToL, Stroop Test, FAS Test, Trail Making Test A and B, Rey-Osterrieth Complex Figure Test (ROCFT), Corsi Block Tapping Test, Digit Span Forward and Backward.

Results: ADHD patients and their parents differed from controls on divided attention and verbal working memory. ADHD subjects differed from controls on ability to control interference and short and long-term memory. Mothers of ADHD children showed a deficit to perform visual search tasks.

Conclusion: Our study indicates that boys with combined ADHD exhibit a selective impairment on divided attention and verbal working memory. The same impairment was showed in parents. Divided attention and working memory represent valid and useful endophenotypes of ADHD for genetic research. A neurogenetic model of ADHD etiology is supportable only for some executive functions.