Depression may impair cognitive function in adult bipolar patients with ADHD

Depressive symptoms may diminish cognitive functioning in adults who have both bipolar disorder and attention-deficit/hyperactivity disorder (ADHD), according to researchers in Spain. The results were recently published in the Journal of Affective Disorders.

Between 10% to 30% of adults with bipolar disorder also present with ADHD. Several clinical studies have found that bipolar patients with comorbid ADHD show notable clinical features, such as more frequent mood episodes, earlier age of onset of bipolar illness, more suicide attempts, and higher rates of substance use disorders, the researchers explained.

Not only are the two disorders clinically correlated, they also have treatment approaches that overlap. The researchers pointed to studies showing that stimulants used for patients with ADHD, such as methylphenidate, had positive effects on symptoms of manic and depressive bipolar disorder.

For this study, the researchers sought to compare functional assessments in three groups of patients: 23 patients with bipolar disorder with comorbid adult ADHD (BD+ADHD), 63 with bipolar disorder only (“pure bipolar disorder” or pBD), and 76 healthy controls. The researchers used a validated functional assessment tool, the Functional Assessment Short Test (FAST), and all subjects were in clinical remission at the time of assessment.

“Our hypothesis was that pBD patients do not differ from BD+ADHD patients in either overall psychosocial functioning or in each specific domain of the FAST. To the best of our knowledge, this is the first study to assess overall and specific domains of functioning in a sample of BD+ADHD participants compared to healthy controls and patients with pure BD,” wrote study investigator and clinical psychologist Anabel Martínez-Aran, PhD, and co-authors at the Bipolar Disorders Program at the Hospital Clinic of Barcelona, in Barcelona, Spain.

As expected, both bipolar-only patients and patients with comorbid BD+ADHD showed lower overall functioning in each domain of the FAST scale compared with control subjects. However, post-hoc testing showed that the BD+ADHD group scored worse than biploar patients in the cognitive domain of the FAST. But after the researchers adjusted for potential confounding variables, they found that only scores on the depression rating scale remained significant for cognitive function.

“Therefore our findings suggest that depressive symptoms in adults with BD+ADHD may negatively influence cognitive functioning,” Dr. Martínez-Aran and colleagues wrote.

Interestingly, the study results showed that bipolar-only patients actually had a higher number of depressive episodes than BD+ADHD patients, which is consistent with previous research. But the results also indicated that the comorbid patients had more subthreshold depressive symptoms than bipolar patients.

“The identification of groups with different levels of psychosocial functioning impairment may help to guide specific and tailored pharmacological and psychological interventions for different patient subgroups with the aim of improving not only psychosocial functioning but also neurocognitive performance,” the authors concluded.