Twelve studies (965 patients) were included in the review. Limited QUADAS results were reported. Not all patients had pathological confirmation of diagnosis. Many studies did not meet reproducibility criteria for EEG methodology and it was often unclear whether interpreters were blinded to diagnosis and clinical information. Confounding appeared to be an issue in some studies.
Alzheimer's disease: Three studies reported a correlation between EEG score and dementia severity and three studies found that EEG matched quantitative EEG in diagnostic utility. The most common EEG finding in early-onset Alzheimer's disease was an increase in slow wave activity (three studies).
Dementia with Lewy bodies: In two studies all patients had abnormal EEGs with loss of alpha dominance. For patients with vascular dementia, in one study patients with high Hachinski scores (>6) were significantly more likely to have focal abnormalities or lateralization compared with patients with a low score; diffuse abnormalities were equally common regardless of the ischaemic score.
Frontotemporal dementia: Results from two studies found that patients had abnormal EEGs but posterior dominant rhythm was preserved.
Results relating to individual studies were reported.