This study was designed to investigate the therapeutic efficacy of est
rogen in female patients with dementia of the Alzheimer type (DAT). Fi
fteen DAT patients with a mean age of (($) over bar x +/- SE) 71.9 +/-
2.4 years were treated with 0.625 mg of conjugated equine estrogens o
rally twice a day for 6 weeks. Of the 15 DAT patients, 4 were diagnose
d as mild, 7 as moderate and 4 as severe. The effects of estrogen on D
AT patients were evaluated by psychometric assessments, behavior ratin
g scales, regional cerebral blood flow (rCBF) measurement and quantita
tive EEG analysis. Psychometric assessments consisted of Mini-Mental S
tate Examination (MMSE) and Hasegawa Dementia Scale (HDS). Dementia sy
ndromes were evaluated by the GBS-Scale (GBSS) and Hamilton Depression
Rating Scale (HDRS). During estrogen replacement therapy (ERT), the m
ean MMSE score (x ($) over bar +/- SE) increased significantly from 11
.6 +/- 1.9 to 13.2 +/- 2.0 at 3 weeks (P<0.01) and 13.8 +/- 2.0 at 6 w
eeks (P<0.001). The mean HDS score increased significantly from 8.6 +/
- 2.1 to 11.5 +/- 2.3 at 3 weeks (P<0.001) and 11.6+/-2.6 at 6 weeks (
P<0.01). Significant improvements in the mean scores of the GBSS and H
DRS were also observed in the estrogen-treated group, but not in the u
ntreated control group with a mean age of 71.2 +/- 2.5 years (n=15). T
he rCBF was measured by single photon emission computed tomography (SP
ECT). ERT increased the mean rCBF significantly in the lower frontal r
egion (P<0.01) and primary motor area (P<0.02) of the right hemisphere
. The mean absolute power delta band values in both left and right fro
ntal EEG (Fp(1) and Fp(2)) (P<0.01) and theta, band values in Fp(2) (P
<0.05) decreased significantly during ERT. It is inferred that ERT sig
nificantly improves cognitive functions, dementia symptoms, regional c
erebral blood flow and EEG activity in female patients with DAT.