The authors examined the presence of specific quantified electroencephalographic (qEEG) changes in dementia patients with relatively lower frontal or parietal blood perfusion as demonstrated by SPECT. Over all brain regions, patients with relatively lower parietal perfusion showed significantly higher theta relative power than demented patients with relatively lower frontal perfusion or normal control subjects. Dementia patients with relatively lower frontal perfusion showed no differences from age-comparable normal control subjects in qEEG variables. These findings 1) suggest that usefulness of qEEG for the diagnosis of dementia is restricted to a subgroup of patients with the typical SPECT pattern of parietal blood hypoperfusion and 2) demonstrate that the qEEG changes typical of dementia are not related to perfusion deficits in frontal brain areas.