[The EEG as an indicator of cholinergic deficit in Alzheimer's disease]

There are tight relationships between the EEG and the activity of the cholinergic system. The excitability of cortical neurons is increased by the ascending cholinergic projections of the nucleus basalis of Meynert. Cholinergic deafferentiation of the cortex leads to an increase of slow-wave EEG activity. Cholinergic deficit is a typical feature of Alzheimer's disease. It is goes along with characteristic EEG alterations, mainly increased activity in the slow frequency bands. The amount of EEG alterations increases as the disease progresses. It is correlated with the severity of symptoms, neuropsychological performance, cerebral perfusion, cerebral glucose utilization and the extent of histopathological changes. EEG alterations are a valuable diagnostic tool in Alzheimer's disease. They may be suited for early diagnosis and may allow the prediction of the therapeutic response to cholinergic drugs.