Medication for Attention-Deficit/Hyperactivity Disorder and Risk for Depression: A Nationwide Longitudinal Cohort Study.

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with high rates of psychiatric comorbidity, including depression. However, it is unclear whether ADHD medication increases or decreases the risk for depression.

METHODS

We studied all individuals with a diagnosis of ADHD born between 1960 and 1998 in Sweden (N = 38,752). We obtained data for prescription of ADHD medication, diagnosis of depression and other psychiatric disorders, and sociodemographic factors from population-based registers. The association between ADHD medication and depression was estimated with Cox proportional hazards regression.

RESULTS

After adjustment for sociodemographic and clinical confounders, ADHD medication was associated with a reduced long-term risk (i.e., 3 years later) for depression (hazard ratio = 0.58; 95% confidence interval, 0.51-0.67). The risk was lower for longer duration of ADHD medication. Also, ADHD medication was associated with reduced rates of concurrent depression; within-individual analysis suggested that occurrence of depression was 20% less common during periods when patients received ADHD medication compared with periods when they did not (hazard ratio = 0.80; 95% confidence interval, 0.70-0.92).

CONCLUSIONS

Our study suggests that ADHD medication does not increase the risk of later depression; rather, medication was associated with a reduced risk for subsequent and concurrent depression.