We measured serum
alpha 1-antichymotrypsin levels in 38 patients with
Alzheimer-type dementia, 89 control subjects, 2 subjects with
Down's syndrome, 20 with
vascular dementia, 18 with
Parkinson's disease, 14 with
spinocerebellar degeneration, 15 with
cerebrovascular disease without
dementia, and 14 with
Duchenne muscular dystrophy. Cerebrospinal fluid (CSF) levels of
alpha 1-antichymotrypsin were also measured in 15 patients with
Alzheimer-type dementia, 26 control subjects, 6 with
vascular dementia, 7 with
cerebrovascular disorder, and 11 with degenerative disorders. In control subjects, there were no age-related changes or sex differences. Serum and CSF levels were significantly and specifically higher in patients with
Alzheimer-type dementia than in other subjects (serum, p less than 0.001; CSF, p less than 0.05). Serum levels of
alpha 1-antichymotrypsin were significantly elevated in the early stage of
Alzheimer-type dementia, whereas there was no definite correlation between serum levels and the degree of
dementia. CSF levels of
alpha 1-antichymotrypsin tended to parallel the severity of
dementia. Serum levels were not correlated with CSF levels. These data indicate that serum and CSF levels of
alpha 1-antichymotrypsin might be independently upregulated in
Alzheimer-type dementia. We concluded that the measurement of serum levels of
alpha 1-antichymotrypsin could be useful as a screening marker for
Alzheimer-type dementia. In addition, CSF levels also could be a useful marker for
Alzheimer-type dementia, because they might reflect the state of
dementia.