Effects of distraction on the contingent negative variation in presenile dementia and normal subjects

The authors recorded contingent negative variation (CNV) in a group of subjects affected by presenile dementia, at the onset of the symptoms, with a slight degree of intellectual deterioration. Recordings were carried out in rest basal conditions and upon administration of an insignificant distracting stimulus. Results were compared with data obtained in a group of normal subjects of the same age under the same experimental conditions. In the patients a marked decrease of the wave was observed upon the administration of a distracting stimulus.