Are men at greater risk for Parkinson's disease than women?(Short Report)

J Neurol Neurosurg Psychiatry 2004;75:637-639. doi: 10.1136/jnnp.2003.020982

Parkinson's disease seems to occur more commonly in men than women based primarily on studies of death rates and prevalence. In recent years, several population based incidence studies of Parkinson's disease that included sex data have been conducted in a variety of populations around the world. To investigate whether these incidence studies suggest an increased risk of Parkinson's disease in men, a meta-analysis was performed of the differences in incidence of Parkinson's disease between men and women reported in seven studies that met the inclusion criteria. A significantly higher incidence rate of Parkinson's disease was found among men with the relative risk being 1.5 times greater in men than women. Possible reasons for this increased risk of Parkinson's disease in men are toxicant exposure, head trauma, neuroprotection by oestrogen, mitochondrial dysfunction, or X linkage of genetic risk factors.

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Whether there is a sex difference in risk for Parkinson's disease (PD) is controversial. (1) PD seems to occur more commonly in men than women based primarily on studies of death rates and prevalence. (1 2) Death rates, however, do not accurately reflect the incidence of PD (3) because of inaccurate diagnoses on death certificates. Likewise, prevalence data are problematic. (1) Prevalence studies are subject to potential sex differences in survival, access to health care, access to the system whereby cases were ascertained for inclusion in the study, and sex differences in the underlying population. (1)

Because incidence of PD represents the number of new cases developed or diagnosed during a specific time interval within a predefined population at risk, incidence measurements are more direct and unambiguous epidemiological estimates of risk for developing PD than are death rates or prevalence. Incidence data from well defined populations obviate a number of concerns with prevalence data, such as differential mortality between men and women.

In recent years, several population based incidence studies of PD that included sex data have been conducted in a variety of populations around the world. To determine whether these incidence studies suggest an increased risk of PD in men, we performed a meta-analysis of the differences in incidence of PD between men and women reported in these studies.

METHODS

The Medline database was searched for …