Catecholamines and cholinergic enzymes in pre-senile and senile Alzheimer-type dementia and down's syndrome

Abstract

Noradrenaline, dopamine, homovanillic acid (HVA), choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) levels were measured in post-mortem brains from 8 cases of pre-senile Alzheimer-type dementia (ATD), 5 cases of senile ATD, 4 cases of Down's syndrome aged 53–57 years, one 27-year-old case of Down's syndrome and 13 controls. In the controls, the concentration of noradrenaline in hypothalamus ( P < 0.05) and mamillary body ( P < 0.02) decreased with age. Compared with age-matched controls, noradrenaline levels in these areas were more markedly reduced in pre-senile ATD ( P < 0.01), the 53–57-year-old cases of Down's syndrome ( P < 0.001) and in the 27-year-old Down's, than in senile ATD (hypothalamus P < 0.05, mamillary body, n.s.). Dopamine and HVA concentrations in caudate nucleus were unaltered in pre-senile or senile ATD but dopamine was decreased ( P < 0.01) in the older cases, although not in the 27-year-old case, of Down's syndrome. In the olfactory tubercle in ATD the level of HVA was unal tered but the activity of ChAT was decreased ( P < 0.01). ChAT activity was reduced in pre-senile ATD ( P < 0.001), the older Down's cases ( P < 0.01) but not the young Down's case, and senile ATD ( P < 0.001) in the temporal cortex and in pre-senile ATD ( P < 0.001) and the older Down's cases ( P < 0.001) but not senile ATD in the caudate nucleus. AChE activity was reduced in the temporal cortex and caudate nucleus in pre-senile ATD ( P < 0.001andP < 0.05, respectively) and Down's syndrome ( P < 0.00) but in only the temporal cortex ( P < 0.05) in senile ATD. The results suggest that there is a greater loss of noradrenergic and cholinergic neurons in pre-senile ATD and Down's syndrome than in senile ATD and that dopamine neurons are unaffected in ATD although altered in activity in cases of Down's syndrome with the clinical and neuropathological characteristics of ATD.