Hormone Replacement Therapy and Risk for Neurodegenerative Diseases

Table 4

RCTs of ERT and Parkinson’s disease.

Study (reference)	Hormone treatment used	Sample Size	Outcome measure	Overall findings
Blanchet [34]	High-dose transdermal E2. Cross-over design with 2 weeks on E2, 2 week washout, and 2 weeks on placebo	8	Therapeutic threshold for levodopa.	All but one participant had levodopa-induced dyskinesia at start of study. After 10 days of E2 treatment a significant reduction was observed in the anti-parkinsonian threshold dose of intravenous levodopa without significantly worsening dyskinesias.
Strijks et al. [35]	17β-estradiol (E2) versus placebo for 8 weeks	12	Motor score from the Unified Parkinson’s Disease Rating Scale (UPDRS); patient report of subjective changes.	No differences in outcome measures between E2 and placebo.
Tsang et al. [36]	CEE versus placebo for 8 weeks	40	UPDRS, timed tapping score, Hamilton Depression Scale, patient self-report.	“On” and “off” times, and motor score on the UPDRS improved with estrogen.
The Parkinson Study Group Poetry I Investigators [37]	CEE versus Placebo for 8 weeks	23	Primary outcome was ability to complete the trial. Other outcome measures included adverse events, UPDRS, “on” time, dyskinesia ratings, and neuropsychological functioning.	The estrogen group showed a trend for improvement on the total and motor UPDRS scores.