Attention-deficit/hyperactivity disorder and comorbid subsyndromal depression: what is the impact of methylphenidate on mood?

Youths with attention-deficit/hyperactivity disorder (ADHD) may develop demoralization or depressive or dysthymic symptoms related to chronic social, familial, and academic difficulties that are associated with their ADHD and are at higher risk for developing mood disorders. We assessed the effectiveness of methylphenidate (MPH) on both ADHD and mood symptoms in children and adolescents diagnosed with ADHD and coexistent subsyndromal depression (SSD).

A group of ADHD patients with SSD (n = 47), aged 8 to 18 years, received 12 weeks of MPH treatment. The severity of depressive and ADHD symptoms was assessed using the Child Depression Rating Scale (CDRS) and the Attention Deficit/Hyperactivity Disorder Rating Scale (ADHD-RS), respectively.

A highly significant decrease in both ADHD-RS and CDRS scores was obtained in the total group (N = 47) after MPH treatment (P = 0.0001 and P = 0.0001, respectively). A significant positive correlation was found between the changes in the CDRS total scores and the ADHD-RS (r = 0.34, N = 47, P = 0.018). However, no such correlation was found in a subgroup (N = 8) of patients with "possible depression" (baseline CDRS score, 65-74; r = 0.026, P = 0.95).

Methylphenidate treatment is effective for both ADHD and SSD symptoms. It seems that ADHD symptoms are less responsive to MPH in patients with relatively high CDRS scores (possible depression) and that those patients may be candidates for selective serotonin reuptake inhibitor treatment as a supplement for MPH. Further, larger, placebo-controlled, double-blind studies are needed to examine the impact of MPH or d-amphetamine on patients with ADHD/SSD and ADHD/major depressive disorder.