Depression and attention deficit disorders in young adults and their connection to right hemisphere function

Abstract

Objectives While depression and attention deficit hyperactivity disorder (ADHD) are highly studied neuropsychiatric disorders, the results are conflicting emphasizing deficits in verbal or visual domain. In this study, we wanted to investigate if the right hemisphere dysfunction model can explain the disorders.

Methods The extensive neuropsychological examination was executed to young adults having depression (N = 10), ADHD (N = 9), both disorders (N = 4), and controls (N = 17) to identify possible deficits in visual reasoning and visual memory functions and attentional orientation.

Results The depressed adolescents showed no deterioration in their ability and memory performance in contrast to the adolescents with ADHD or both disorders who had verbal memory problems besides performing significantly worse in verbal (but not visual) ability tasks. As for the visual memory, the adolescents having both disorders could be detected only by the most demanding, visuospatial (12 shapes) learning task, in which they made most errors and needed more trials to complete the task compared to controls. In attentional tendencies, all individuals remembered objects better on their left side in an easy task but their visual attention was directed more to their right side in more demanding visual memory task.

Conclusions Despite the small group sizes, our results suggest that adolescents with ADHD and both disorders might be identified by their lowered verbal ability and verbal memory scores. In visual domain, identifying them by neuropsychological tests is more difficult. Thus, the right hemisphere dysfunction model is not good candidate to
explain the core deficits in young adults with depression and ADHD. Rather, we suggest that these disorders might be approached with the left hemisphere (higher functioning in depression and lower functioning in ADHD) model.