In order to clarify the biological features of age-associated memory impairment(AAMI) we investigated dilute tropicamide eye drop tests, serum α 1-antichimotrypsine (α 1-ACT) concentrations and apolipoprotein E epsilon 4 allele (ApoE4) frequencies in the normal control elderlys, AAMI subjects, the patients with Alzheimer type dementia(ATD) of early onset type(Alzheimer's disease : AD) and late onset type(senile dementia of Alzheimer's type : SDAT), and those with vascular dementia(VD). Using strict inclusion and exclusion criteria (NINCDS-ADRDA), we recruited 18 patients of AD (63.1±5.8 years old), 26 of SDAT(77.2±4.7 y.o.), 27 of VD(75.0±6.7 y,o.). Regarding AAMI and non-demented controls (C), 24(64.3±12.2 y.o.) and 21(67.6±9.3 y.o.) of persons were enrolled, respectively.
Results and conclusion :
1) In response to the administration of 0.01% of tropicamide, the value of AAMI group(8.6±6.2%) was nearly equal to that of C group(7.8±5.5%), which tended to be significant to AD-(23.3±19.1%) and SDAT groups(22.0±14.5%)(p<0.1). However, there was no significant differences to either AD or SDAT group.
2) Serum α1-ACT values were 278.10±36.3(μg/ml) in AAMI, 259.6±32.7 in C, 303.7±87.8 in AD, 324.2±82.6 in SDAT, 314.7±72.5 in VD group, respectively, so that there was a significant difference only between SDAT and C group (p<0.05).
3) The ε4 allele frequency showed the highest value in SDAT group(40.0±40.8%), and the value of AAMI(20.8±29.2%) was beween C(12.5±27.5%) and AD(31.3±40.3%). However, there was no significant difference among each group.
Our results suggest that AAMI might not be a distinct clinical entity, but the one which consists of a variety of group such as entirely normal eldelys and a very early stage of Alzheimer Type Dementia.