Mental health symptoms as preclinical indicators of dementia: a Whitehall II cohort study

INTRODUCTION: Changes in mental health symptoms, and their timing in the preclinical period of dementia, are not well characterised. METHODS: We followed 5,495 Whitehall II participants (median age 68.5; 72.1% male) from their mental health symptoms assessment using the Clinical Interview Schedule-Revised (CIS-R) starting in 2012/13 to dementia diagnosis, death, or 2024. Linear mixed effects regression assessed CIS-R score changes preceding dementia. Flexible parametric models estimated associations of mental health symptoms with dementia. RESULTS: Total CIS-R score increased (2.56 points [0.85-4.27]) in the 12 years preceding dementia. Having any mental health condition was associated with dementia in the short-term (HR at 3 years=4.04 [2.53-6.50]) but not the long-term (HR at 6 years=1.26 [0.63-2.49]). This pattern held for severe mental health conditions, concentration problems, depression, irritability, fatigue, anxiety, and worry. DISCUSSION: Awareness of mental health symptoms as preclinical indicators of dementia in the short-term may support timely diagnosis of dementia.