Around one-half of women and one-third of men will develop dementia, stroke, or parkinsonism during their lifetime, according to a study published online ahead of print October 2 in the Journal of Neurology, Neurosurgery & Psychiatry.
The population-based Rotterdam study involved 12,102 individuals (57.7% women) who were ages 45 or older and free of neurologic disease at baseline. This cohort was followed for 26 years. Silvan Licher, a PhD student in the Department of Epidemiology at Erasmus MC University Medical Center Rotterdam in the Netherlands, and colleagues found that a 45-year-old woman had a 48.2% overall remaining lifetime risk of developing dementia, stroke, or parkinsonism, while a 45-year-old man had a 36.3% lifetime risk.
“There are currently no disease-modifying drugs available for dementia and most causes of parkinsonism, and prevention of stroke is hampered by suboptimal adherence to effective preventive strategies or unmet guideline thresholds,” the authors wrote. “Yet a delay in onset of these common neurologic diseases by merely a few years could reduce the population burden of these diseases substantially.”
Women age 45 had a significantly higher lifetime risk than men of developing dementia (31.4% vs 18.6%, respectively) and stroke (21.6% vs 19.3%), but the risk of parkinsonism was similar between the sexes. Women also had a significantly greater lifetime risk of developing more than one neurologic disease, compared with men (4% vs 3.1%), largely because of the overlap between dementia and stroke.
At age 45, women had the greatest risk of dementia, but as men and women aged, their remaining lifetime risk of dementia increased relative to other neurologic diseases. After age 85, 66.6% of first diagnoses in women and 55.6% in men were dementia. By comparison, first manifestation of stroke was the greatest threat to men age 45. Men also were at a significantly higher risk for stroke at a younger age—before age 75—than were women (8.4% vs 5.8%, respectively). In the case of parkinsonism, the lifetime risk peaked earlier than it did for dementia and stroke and was relatively low after age 85, with no significant differences in risk between men and women.
The authors considered what effect a delay in disease onset and occurrence might have on remaining lifetime risk for neurologic disease. They found that a one-, two-, or three-year delay in the onset of all neurologic disease was associated with a 20% reduction in lifetime risk in individuals age 45 or older, and a greater than 50% reduction in risk in the oldest. A three-year delay in the onset of dementia reduced the lifetime risk by 15% for men and women age 45 and conveyed a 30% reduction in risk to those age 45 or older.
The Rotterdam study is supported by Erasmus MC and Erasmus University Rotterdam; the Netherlands Organization for Scientific Research; the Netherlands Organization for Health Research and Development; the Research Institute for Diseases in the Elderly; the Netherlands Genomics Initiative; the Ministry of Education, Culture, and Science; the Ministry of Health, Welfare, and Sports; the European Commission and the Municipality of Rotterdam; the Netherlands Consortium for Healthy Aging; and the Dutch Heart Foundation.