Determinants of Psychomotor Slowing in Older Adults With Depressive Disorder

BACKGROUND: Psychomotor slowing in older adults with depressive disorder (DD) has been associated with a poor prognosis. Whether psychomotor slowing is associated with depression itself, age-related physical and cognitive factors, or both, is important to personalize treatments. We examined the unique contributions of different determinants of psychomotor slowing in older adults with DD. METHODS: Baseline data of the Routine-Outcome-Monitoring for Geriatric Psychiatry and Science (ROM-GPS) study, and the Netherlands Study of Depression in Older persons (NESDO) were used to include a total of N = 521 patients (N = 143 ROM-GPS; N = 378 NESDO) aged ≥ 60 years who fulfilled DSM-criteria of a DD. Psychomotor slowing was measured multidimensionally with motor slowing (gait speed), cognitive slowing (processing speed), and subjective slowing (item-23 of Inventory-of-Depressive-Symptoms scale). Potential determinants were categorized into demographics, depression-related, physical and cognitive health, lifestyle, and psychosocial factors. Multivariate linear regression analyses were applied for each component of slowing. RESULTS: The minority (7.3%) had slowing on all three components. Moderate correlations were found between motor and cognitive slowing, whereas no or low correlations were found between subjective slowing and either motor or cognitive slowing. Motor slowing was associated with higher age, female sex, polypharmacy, and higher body-mass-index. Cognitive slowing was associated with diminished global cognitive performance. Subjective slowing with higher depression severity and worse global cognitive performance. CONCLUSIONS: Psychomotor slowing in older adults with DD is complex, consisting of a motor, cognitive, and subjective component, all of which have a unique phenotype. Because motor and cognitive slowing are not closely related to depression severity, it suggests that in older people with DD other age-related factors are more important determinants, which should be taken into account for optimizing treatment.