Aging of human alpha rhythm.

Alpha rhythm (AR) changes are the most pronounced electroencephalogram phenomenon in the aging brain. We analyzed them based on the inherent AR structure obtained by parallel factor analysis decomposition in the cortical source space. AR showed a stable multicomponent structure in 78% of sixty 20- to 81-year-old healthy adults. Typically, it consists of 2 components. The distribution of the higher frequency occipito-parietal component widens with age, with its maximum moving from BA18/19 to BA37. The low-frequency component originating from the occipito-temporal regions in young adults also moves anteriorly with age, while maintaining its maximum within BA37. Both components slow down by 1 Hz over the adult lifespan. The multicomponent AR is more common in younger subjects, whereas a single-component AR in older subjects. This uneven occurrence as well as the increasing spatial and frequency overlaps between components suggest transformation of the multicomponent AR into the single-component AR with age. A detailed knowledge of AR component structure would be useful to monitor age-related neurodegenerative processes in humans.