Age-related changes of neuronal counts in the human pedunculopontine nucleus

Cholinergic neurons in the basal forebrain and the upper brainstem undergo changes during aging and in dementia of the Alzheimer type, Parkinson's disease and progressive supranuclear palsy. Little is known about the effect of age on neurons in the tegmental pedunculopontine nucleus. Cholinergic neurons revealed by choline acetyltransferase immunohistochemistry were quantified in the brains of 20 subjects who died without neurological disorder between 28 and 101 years of age. A U-shaped relationship between cell counts and age was found, namely, a decrease in counts between 28 and 70, a minimum between 80 and 91 years of age, and, in four subjects aged 98-101 years counts comparable to those of subjects having died between 28 and 65 years. The findings suggest that the loss of cholinergic pedunculopontine nucleus neurons is not linear. In centenarians age-related neuronal decrease in pedunculopontine nucleus neurons may be slower or the stock of pedunculopontine nucleus neurons greater than in subjects dying earlier.