Slowing on quantitative EEG is associated with transition to dementia in mild cognitive impairment

Abstract

Electroencephalographic (EEG) abnormalities are greater in mild cognitive impairment (MCI) with Lewy bodies (MCI-LB) than in MCI due to Alzheimer’s disease (MCI-AD) and may anticipate onset of dementia. We aimed to assess whether quantitative EEG (qEEG) slowing would predict a higher annual hazard of dementia in MCI across these aetiologies. MCI patients (n=92) and healthy comparators (n=31) provided qEEG recording and underwent longitudinal clinical and cognitive follow-up. Associations between qEEG slowing, measured by increased theta/alpha ratio, and clinical progression from MCI to dementia were estimated with a multi-state transition model to account for death as a competing risk, while controlling for age, cognitive function, and aetiology classified by an expert consensus panel. Over a mean follow up of 1.5 years (SD = 0.5) fourteen cases of incident dementia and five deaths were observed. Increased theta/alpha ratio on qEEG was associated with increased annual hazard of dementia (Hazard Ratio = 1.84, 95% CI: 1.01–3.35). This extends previous findings that MCI-LB features early functional changes, showing that qEEG slowing may anticipate onset of dementia in prospectively-identified MCI.