Effect of reproductive factors and postmenopausal hormone use on the risk of Parkinson disease.
OBJECTIVE
Parkinson disease (PD) is less common in women possibly because of hormonal or reproductive influences. The objective of this study was to evaluate the associations of reproductive factors and postmenopausal hormone use with the risk of PD among postmenopausal women.


METHODS
Incident cases (n = 178) and randomly selected age-matched controls (n = 189) who were members of the Kaiser Permanente Medical Care Program (KPMCP) of Northern California participated in the study conducted during the years 1994 to 1995. Statistical analyses were carried out using logistic regression.


RESULTS
The association of postmenopausal hormone use with PD risk depended on the type of menopause. Among women with history of a hysterectomy with or without an oophorectomy, estrogen use alone was associated with a 2.6-fold increased risk (adjusted odds ratio (OR) 2.6, 95% CI: 1.1 to 6.1) and significant trends in the risk of PD were observed with increasing duration of estrogen use, but disease risk was not influenced by recency of use. In contrast, among women with natural menopause, no increased risk of PD was observed with hormone use (estrogen alone or a combined estrogen-progestin regimen). Early age at final menstrual period (44 years or younger) was associated with reduction in risk (adjusted OR 0.5, 95% CI: 0.3 to 1.0). Age at menarche and parity were not associated with the risk of PD.


CONCLUSIONS
Postmenopausal use of estrogen alone may increase the risk of Parkinson disease (PD) among women with a hysterectomy. Among women with natural menopause for whom the usual treatment is combined estrogen-progestin therapy, no increased risk of PD was observed.
Popat
R A
RA
Division of Epidemiology, Department of Health Research and Policy, Stanford University School of Medicine, Stanford, CA 94305-5405, USA. rpopat@stanford.edu
Van Den Eeden
S K
SK
Tanner
C M
CM
McGuire
V
V
Bernstein
A L
AL
Bloch
D A
DA
Leimpeter
A
A
Nelson
L M
LM
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D000075202:Contraindications; D004338:Drug Combinations; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects*; D016015:Logistic Models; D008593:Menopause / Q000378:metabolism; D008875:Middle Aged; D010052:Ovariectomy / Q000009:adverse effects; D010300:Parkinson Disease / Q000453:epidemiology / Q000209:etiology* / Q000378:metabolism; D011374:Progesterone / Q000627:therapeutic use; D012307:Risk Factors
D004338:Drug Combinations; D004967:Estrogens; D011374:Progesterone