Significance of Focal Electroencephalographic Changes in the Elderly

One-third of the population more than 60 years old will have an abnormal electroencephalogram of a focal type, consisting primarily of slow waves. This abnormality is usually maximal over the anterior temporal area and occurs more often on the left side of the brain. It is probably of vascular origin, although no consistent correlation has been established with physical or psychologic impairment. Its predilection for the left hemisphere is not related to cerebral dominance. The likelihood of seizures is not increased. The clinician is cautioned to avoid interpreting this finding as evidence of an expanding intracranial lesion.