OBJECTIVE: The authors evaluated the potential of methylphenidate to improve antidepressant response to citalopram, as assessed by clinical and cognitive outcomes, in elderly depressed patients. METHOD: The authors conducted a 16-week randomized double-blind placebo-controlled trial for geriatric depression in 143 older outpatients diagnosed with major depression comparing treatment response in three treatment groups: methylphenidate plus placebo (N=48), citalopram plus placebo (N=48), and citalopram plus methylphenidate (N=47). The primary outcome measure was change in depression severity. Remission was defined as a score of 6 or less on the Hamilton Depression Rating Scale. Secondary outcomes included measures of anxiety, apathy, quality of life, and cognition. RESULTS: Daily doses ranged from 20 mg to 60 mg for citalopram (mean=32 mg) and from 5 mg to 40 mg for methylphenidate (mean=16 mg). All groups showed significant improvement in depression severity and in cognitive performance. However, the improvement in depression severity and the Clinical Global Impressions improvement score was more prominent in the citalopram plus methylphenidate group compared with the other two groups. Additionally, the rate of improvement in the citalopram plus methylphenidate group was significantly higher than that in the citalopram plus placebo group in the first 4 weeks of the trial. The groups did not differ in cognitive improvement or number of side effects. CONCLUSIONS: Combined treatment with citalopram and methylphenidate demonstrated an enhanced clinical response profile in mood and well-being, as well as a higher rate of remission, compared with either drug alone. All treatments led to an improvement in cognitive functioning, although augmentation with methylphenidate did not offer additional benefits.