Very few studies addressed genetic influences on human EEG at the other end of the lifespan. One of the early twin studies of older adults (Heuschert, 1963) including 26 MZ twins at the age of 50-79 years noted a striking intra-pair similarity with respect to both general EEG characteristics and specific aging-related EEG changes such as slowing of the alpha-rhythm, increased variability of alpha-frequency, and diffuse slow-wave activity. This similarity was observed despite substantial differences in lifestyles and experiences of the twins. Interestingly, a blind matching of co-twins using their EEG was successful in 24 cases out of 26. This study, although based on a small sample, points to the importance of genetic factors in brain aging and suggests the possibility that quantitative EEG could potentially serve as a marker of genetically determined age-related changes in brain function, both normal and pathological (e.g. in Alzheimer's disease). This possibility should be explored in future twin EEG studies focused on the genetic determinants of individual differences in brain aging.
