Depressive symptoms predict memory decline in Essential Tremor

Introduction: Essential tremor (ET), a common movement disorder, is characterized by motor, cognitive and psychiatric symptoms. Depressed mood, a symptom of ET, has historically been viewed as a psychological response to disability. However, depressive symptoms are emerging as a predictor of cognitive decline across several clinical populations. We examined if depressive symptoms predict decline in global cognition, memory, and executive functioning among older adults with ET. Methods: 125 cognitively normal participants with ET completed three in-person assessments of cognition, mood, and motor symptoms at baseline, 18 months, and 36 months; baseline data were collected from July 2014–July 2016. Depressive symptoms were measured with the Geriatric Depression Scale. Cognitive functioning was measured via a 3-4 hour neuropsychological evaluation. Generalized linear regression models examined depressive symptoms as a predictor of decline in global cognition, executive functioning (EF), and memory. Results: Participants were grouped according to a median split (GDS <5 versus ≥ 5) due to the bimodal distribution of the data. In unadjusted models, depressive symptoms did not predict change in global cognition (b = −0.002, p = .502) or EF (b = 0.000, p = .931), however individuals with GDS ≥ 5 demonstrated faster memory decline in unadjusted (b = −0.008, p = .039) and adjusted models (b = −0.009, p = .019). Conclusion: The presence of 5 or more depressive symptoms predicted mildly faster memory decline in cognitively normal older adults with ET over 36 months. We discuss potential mechanisms and clinical implications.