Prefrontal neuropsychological predictors of treatment remission in late-life depression

Recent studies suggest that neuropsychological measures involving the prefrontal cortex are associated with treatment remission in late-life depression. To further explore this issue, we studied the neuropsychological performance of 110 depressed individuals aged 60 years and over who are participating in an ongoing pharmacologic treatment study. Participants were clinically depressed at entry to the study as rated by the Montgomery - Asberg Depression Rating Scale (MADRS greater than or equal to15), at which time they also completed a neuropsychological assessment that included measures of prefrontal/executive functions. A geriatric psychiatrist treating the participant using a standardized pharmacologic treatment algorithm evaluated the participant at baseline and 3-month follow-up, completing a MADRS at both visits. Using logistic discriminative procedures to predict depression remission at 3 months while controlling for age, gender, education, ethnicity, and baseline MADRS severity, we found that perseverative responses during verbal initiation tasks significantly predicted remission status ( MADRS <7). This finding is consistent with previous single-agent treatment studies suggesting a relationship between prefrontal neuropsychological function and treatment response in late-life depression. The current results, however, appear to differentiate verbal perseveration from verbal initiation as the cognitive process that is most associated with poor treatment response. By extension, we suggest that orbitofrontal prefrontal cortex may play a role in sustaining perseverative processing in geriatric depression.