The electroencephalogram in the senile psychoses

Abstract

Analysis was made of the EEGs of 50 mentally normal seniles and 104 patients suffering from senile psychosis. The following are the results and conclusions: 1. 1. Twenty-four per cent of the normal group possessed abnormal EEGs. In normal old persons slow activity does not appear to be a characteristics EEG abnormality, in fact there is a tendency for paroxysmal fast activity to be prominent. Old age is however associated with a significant decrease in alpha frequency, amplitude and per cent time. 2. 2. Fifty-four per cent of the psychotic seniles possessed abnormal EEGs. The characteristic abnormality of the senile psychoses is diffuse delta and theta rhythm or diffuse theta rhythm. There is an association between incidence of non-normal EEGs and degree of senile dementia, the likelihood of a normal EEG being lessened with increased dementia. 3. 3. A significant relationship was found between alpha index and degree of senile dementia: alpha index decreases with increased dementia. 4. 4. The finding that the incidence of abnormal EEGs among depressed and paranoid seniles was not significantly different from that in other forms of senile psychosis, was adduced as favouring a common aetiology for these conditions. 5. 5. Amongst 10 preseniles, only 1 possessed an abnormal EEG and 2 were questionable. Study of larger numbers is indicated before any definite conclusions can be drawn from this finding.