Objective:

To investigate whether electroencephalogram (EEG) slowing in cognitively healthy adults in the general population predicts future dementia diagnosis.

Background:

EEG slowing is commonly seen in dementia. However, it is unclear whether EEG slowing in the absence of cognitive impairment is predictive of future dementia.

Design/Methods:

2800 cognitively unimpaired older adults from the Osteoporotic Fractures in Men Study (MrOS) and the Study of Osteoporotic Fractures (SOF) underwent in-home polysomnography (PSG) at baseline and returned for follow-up during the subsequent 12 years. Theta-to-alpha ratio (TAR) was calculated during non-REM sleep using power spectral analysis of the EEG. Multivariable logistic regression was used to estimate odds ratios (OR) for incident dementia according to quartiles of baseline TAR.

Results:

Compared with participants in the lowest quartile of TAR, those in the highest quartile had a 2.2-fold risk of developing dementia in MrOS and a 10.0-fold risk of developing dementia in SOF (P’s <0·01). Furthermore, a higher TAR at baseline and greater increase in TAR over time, were associated with greater genetic risk for dementia, faster cognitive decline, faster epigenetic ageing measured by DunedinPACE, and increased risk of all-cause mortality (P’s <0·05).

Conclusions: