Around one-half of women and one-third of men will develop dementia, stroke, or parkinsonism during their lifetime, based on results from the population-based Rotterdam study published in the Oct. 1 online edition of the Journal of Neurology, Neurosurgery & Psychiatry.
The study involved 12,102 individuals (57.7% women) who were aged 45 years or older and free from neurologic disease at baseline who were followed for 26 years.
Silvan Licher, MD, and colleagues from the University Medical Center Rotterdam (the Netherlands) 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 aged 45 years 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%, P less than .001), 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 years, 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 aged 45. Men were also at a significantly higher risk for stroke at a younger age – before age 75 years – than were women (8.4% vs. 5.8%).
In the case of parkinsonism, the lifetime risk peaked earlier than it did for dementia and stroke, and was relatively low after the age of 85 years, with no significant differences in risk between men and women.
The authors also considered what effect a delay in disease onset and occurrence might have on remaining lifetime risk for neurologic disease. They found that a 1, 2, or 3-year delay in the onset of all neurologic disease was associated with a 20% reduction in lifetime risk in individuals aged 45 years or older, and a greater than 50% reduction in risk in the very oldest.
A 3-year delay in the onset of dementia reduced the lifetime risk by 15% for both men and women aged 45 years and granted a 30% reduction in risk to those aged 45 years 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 Ageing, and the Dutch Heart Foundation. No conflicts of interest were declared.
SOURCE: Licher S et al. JNNP. 2018 Oct 1. doi: 10.1136/jnnp-2018-318650.