Attention Deficit/Hyperactivity Disorder symptoms and cognitive abilities in the late-life cohort of the PATH through life study.

Attention Deficit/Hyperactivity Disorder (ADHD) is a common neuropsychiatric disorder that has not been well studied in older adults. In this study we examined relationships between ADHD symptoms and cognitive ability and compared them between middle-age (MA; 48-52 years) and older-age (OA; 68-74 years) adults sampled from the same population. ADHD, mood disorder symptoms and cognitive abilities were assessed in a large population-based sample (n = 3443; 50% male). We measured current ADHD symptoms using the adult ADHD Self-Report Scale (ASRS), which we found to have the same underlying structure in both cohorts. Older adults reported significantly lower levels of ADHD symptoms and 2.2% of the OA cohort scored equal or above the ASRS cut-off score of 14 (which has been previously associated with ADHD diagnosis) compared with 6.2% of MA adults. Symptom levels were not significantly different between males and females. Using multi-group structural equation modelling we compared ADHD symptom-cognitive performance relationships between the two age groups. Generally higher ADHD symptoms were associated with poorer cognitive performance in the MA cohort. However, higher levels of inattention symptoms were associated with better verbal ability in both cohorts. Surprisingly, greater hyperactivity was associated with better task-switching abilities in older adults. In the OA cohort ADHD symptom-cognition relationships are indirect, mediated largely through the strong association between depression symptoms and cognition. Our results suggest that ADHD symptoms decrease with age and that their relationships with co-occurring mood disorders and cognitive performance also change. Although symptoms of depression are lower in older adults, they are much stronger predictors of cognitive performance and likely mediate the effect of ADHD symptoms on cognition in this age group. These results highlight the need for age-appropriate diagnosis and treatment of comorbid ADHD and mood disorders.