The high lifetime risk of neurological disease

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NeurologyOne in two women and one in three men will develop dementia, or Parkinson’s disease, or have a stroke in their lifetime. according to a large 26-year study. Those diagnosed with one of the three conditions had a higher prevalence of high blood pressure, abnormal heart rhythm, high cholesterol and type 2 diabetes at the start of the monitoring period.

The researchers, from the University Medical Centre Rotterdam in the Netherlands, said preventive measures could “substantially” reduce the burden of the illnesses.

The health of 12,102 people was monitored between 1990 and 2016, with all participants initially under the age of 45. During this period 1,489 were diagnosed with dementia and 263 with parkinsonism – the generic term for a range of symptoms that can be seen in someone with Parkinson’s disease – while 1,285 had a stroke.

The overall risk of a 45-year-old later developing one of the three conditions was 48% for women and 36% for men, the researchers said. Dementia was of greatest concern for women, who at 45 years old had a 25.9% risk of going on to develop the condition, compared with 13.7% for men.

“These are the three most common neurological diseases in the elderly population and also some of the most feared,” said Silvan Licher, one of the authors of the study, who said they embarked on the study to show the burden of neurological diseases on elderly people. In middle age, there is a great deal of focus on heart disease and cancer, but diseases of the brain in later life get less attention and are less researched. For people over 85, dementia is the greatest risk, he said.

Many people suffer from more than one disease in later life. “We noticed that there is much overlap between them,” said Licher. “People do not just have one disease in later life but can have two or three at the same time.”

Dr Carol Routledge, director of research at Alzheimer’s Research UK, said in the report: “This large study underscores the enormous impact that neurological illnesses have across society and how women are disproportionately affected, particularly when it comes to dementia.”

Those diagnosed with one of the three conditions were found to have a higher prevalence of high blood pressure, abnormal heart rhythm, high cholesterol and type 2 diabetes at the start of the monitoring period.

“These findings strengthen the call for prioritising the focus on preventative interventions at population level, which could substantially reduce the burden of common neurological diseases in the ageing population,” the authors said.

They estimate that if onset of dementia, parkinsonism and stroke was delayed by one to three years, the remaining risk of developing the conditions could be cut by 20% among 45-year-olds and more than 50% in those older than 85.

Routledge said in the report that it was “crucial” that efforts to find a drug that could delay the onset of dementia symptoms were increased. “For most of us, our individual risk of illnesses like dementia is not set in stone and there are things we can all do to help maintain a healthy brain,” she said.

“The best current evidence suggests that eating a balanced diet, controlling our weight, staying physically active, not smoking, only drinking within the recommended limits and keeping blood pressure and cholesterol in check are all associated with better brain health into old age.”

Abstract
Objective: To quantify the burden of common neurological disease in older adults in terms of lifetime risks, including their co-occurrence and preventive potential, within a competing risk framework.
Methods: Within the prospective population-based Rotterdam Study, we studied lifetime risk of dementia, stroke and parkinsonism between 1990 and 2016. Among 12 102 individuals (57.7% women) aged ≥45 years free from these diseases at baseline, we studied co-occurrence, and quantified the combined, and disease-specific remaining lifetime risk of these diseases at various ages for men and women separately. We also projected effects on lifetime risk of hypothetical preventive strategies that delay disease onset by 1, 2 and 3 years, respectively.
Results: During follow-up of up to 26 years (156 088 person-years of follow-up), 1489 individuals were diagnosed with dementia, 1285 with stroke and 263 with parkinsonism. Of these individuals, 438 (14.6%) were diagnosed with multiple diseases. Women were almost twice as likely as men to be diagnosed with both stroke and dementia during their lifetime. The lifetime risk for any of these diseases at age 45 was 48.2% (95% CI 47.1% to 51.5%) in women and 36.2% (35.1% to 39.3%) in men. This difference was driven by a higher risk of dementia as the first manifesting disease in women than in men (25.9% vs 13.7%; p<0.001), while this was similar for stroke (19.0%vs18.9% in men) and parkinsonism (3.3% vs 3.6% in men). Preventive strategies that delay disease onset with 1 to 3 years could theoretically reduce lifetime risk for developing any of these diseases by 20%–50%.
Conclusion: One in two women and one in three men will develop dementia, stroke or parkinsonism during their life. These findings strengthen the call for prioritising the focus on preventive interventions at population level which could substantially reduce the burden of common neurological diseases in the ageing population.

Authors
Silvan Licher, Sirwan KL Darweesh, Frank J Wolters, Lana Fani, Alis Heshmatollah, Unal Mutlu, Peter J Koudstaal, Jan Heeringa, Maarten JG Leening, M Kamran Ikram, M Arfan Ikram

The Guardian report
Journal of Neurology, Neurosurgery & Psychiatry abstract


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