There are some indications that anxiety in midlife is associated with an increased risk of dementia, even after allowing for any anxiety which might have been expected to arise as a result of prodromal cognitive decline / pre-clinical dementia.
Gimson, A. Schlosser, M. [and] Huntley, JD. [et al] (2018). Support for midlife anxiety diagnosis as an independent risk factor for dementia: a systematic review. BMJ Open. April 30th 2018; 8(4): e019399.