New findings from a large national
claims database show the use of cholesterol-lowering statin drugs to
be associated with an increased risk for Parkinson's disease (PD),
contrary to previous research suggesting the drugs have a protective
effect for PD.
"We identified 20,000 Parkinson's
disease patients and looked at whether using statins was associated
with a higher or lower risk, and we found people using statins have a
higher risk of the disease, so this is the opposite of what has been
hypothesized," senior author Xuemei Huang, MD, PhD, vice chair
for research at Penn State College of Medicine, Hershey,
Pennsylvania, told Medscape Medical News.
While high cholesterol has been shown
to have a protective effect on the risk for PD, the role of statin
use has been the subject of debate.
In looking at the issue in a previous
study of their own, Dr Huang and colleagues in fact found an
increased risk associated with statin use, and they sought in the new
study to further explore the association in a much larger cohort.
For the new study, presented here at
the American Neurological Association (ANA) 2016 Annual Meeting, the
researchers turned to data from the MarketScan Commercial Claims and
Encounters database, including information on 30,343,035 persons aged
40 to 65 years between January 1, 2008, and December 31, 2012.
In the cross-sectional analysis, the
use of cholesterol-lowering drugs, including statins or nonstatins,
was associated with a significantly higher prevalence of Parkinson's
disease (odds ratio [OR], 1.61 - 1.67; P less than .0001) after
adjustment for age, sex, and other comorbidities, such as
hyperlipidemia, diabetes, hypertension, and coronary artery disease.
For a comparative neurodegenerative
group, the researchers also looked at the association of statin with
diagnosis of Alzheimer's disease but found only a minimal association
(OR, 1.01 - 1.12; P = .055).
The associations of
cholesterol-lowering medications with PD were strongest among
patients with hyperlipidemia, and there were no significant
differences between lipophilic or hydrophilic statins, as well as the
other nonstatin cholesterol-lowering drugs, in their effect on PD
risk.
"We know that overall weight of
the literature favors that higher cholesterol is associated with
beneficial outcomes in Parkinson's disease, so it's possible that
statins take away that protection by treating the high cholesterol,"
Dr Huang explained.
"Another possibility is that
statins can block not only the cholesterol synthesis but also
synthesis of coenzyme Q10 that is essential for cell function."
The researchers also stratified persons
according to how long they had been receiving treatment by using a
lagged matched case-control analysis of 2458 pairs of PD cases and
controls.
In the cross-sectional analysis, both
statins and nonstatin cholesterol-lowering drugs were associated with
PD, but in the lagged case-control analysis of treatment duration,
only statins remained significantly associated with PD risk.
"The increased risk of Parkinson's
is more likely when statins are first used, so we think it could be
that the statins 'unmasked' Parkinson's," Dr. Huang said.
"Namely, people may be already on the way to Parkinson's and
when they use statins to control the high cholesterol, it gives
Parkinson's a push to reveal its clinical symptoms.
"Based on this data, we think
caution should be taken before advancing statins to be protective of
Parkinson's disease," she added. "The data are not clear
yet."
A meta-analysis published earlier this
year in the journal Pharmacoepidemiology and Drug Safety suggests
that one reason for the inconsistencies in evidence of the role of
statins is that many studies fail to adjust for cholesterol levels.
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