Neurocognitive Correlates of Response to Treatment in Late-Life Depression

Abstract

Depression is often associated with neurocognitive deficits in older adults, particularly in the domains of information processing speed, episodic memory, and executive functions. Greater neurocognitive dysfunction while depressed is associated with a less effective treatment response; however, questions remain about the specific variables that characterize patients showing low treatment response and persistent cognitive deficiencies. The authors examined neurocognitive variables that differentiated patients who showed robust versus weak responses to antidepressant therapy. The baseline sample included 110 women and 67 men, with a mean age of 69.1 years (SD = 6.9) and mean education of 14 years (SD = 3.3). Patients enrolled in a treatment study completed both a structured diagnostic assessment for depression and neuropsychological testing at study entry and 1-year follow-up. Clinicians rated patient depression using the Montgomery-Asberg Depression Rating Scale. Neuropsychological assessments consisted of prose recall and percent retention (Wechsler Memory Scale -III Logical Memory), word-list recall, attention and visuomotor processing speed (Trail Making A, Symbol Digit Modalities Test), and mental flexibility (Trail Making B). Patients underwent treatment for depression following the guidelines of the Duke Somatic Treatment Algorithm for Geriatric Depression approach. Individuals who demonstrated the greatest improvement in mood symptoms at follow-up exhibited better prose recall and faster processing speed at baseline than individuals who demonstrated weaker treatment responses. These differences remained after controlling for depression severity at both time-points. The current results suggest that better pretreatment cognitive function, particularly in verbal memory, is associated with a greater treatment response in late-life depression.