The onset of Alzheimer鈥檚 disease: the importance of family history
You鈥檙e about to turn 60, and you鈥檙e fretting. Your mother has had Alzheimer鈥檚 disease since the age of 65. At what age will the disease strike you? A Canadian study published in JAMA Neurology shows that the closer a person gets to the age at which their parent exhibited the first signs of Alzheimer鈥檚, the more likely they are to have amyloid plaques, the cause of the cognitive decline associated with the disease, in their brain.
In this study involving a cohort of 101 individuals, researcher Sylvia Villeneuve (Douglas Mental Health University Institute; CIUSSS de l鈥橭uest-de-l鈥櫭巐e-de-Montr茅al) shows that the difference between a person鈥檚 age and the age of their parent at the onset of the disease is a more important risk factor than their actual age.
A 60-year-old whose mother developed Alzheimer鈥檚 at age 63 would be more likely to have amyloid plaques in their brain than a 70-year-old whose mother developed the disease at age 85,鈥� explains Villeneuve, an assistant professor at 捆绑SM社区 and a core faculty member at The Neuro鈥檚 McConnell Brain Imaging Centre.
Her team of scientists also found that the genetic impact of Alzheimer鈥檚 disease is much greater than previously thought.
鈥淯pon examining changes in the amyloid biomarker in the cerebrospinal fluid samples from our subjects, we noticed that this link between parental age and amyloid deposits is stronger in women than in men. The link is also stronger in carriers of the ApoE4 gene, the so-called 鈥楢lzheimer鈥檚 gene鈥�,鈥� says Villeneuve.
Towards earlier detection of the disease
The researcher and her team successfully duplicated their results in two independent groups, one, consisting of 128 individuals from a University of Washington-St. Louis cohort, the other consisting of 135 individuals from a University of Wisconsin-Madison cohort. They also reproduced their results using an imaging technique that enables one to see amyloid plaques directly in the brains of living persons.
Their study is paving the way for the development of inexpensive methods for the early identification of people at risk for Alzheimer鈥檚 disease. According to the Alzheimer Society of Canada, 564,000 Canadians currently have Alzheimer鈥檚 disease or another form of dementia. The figure will be 937,000 within 15 years. Presently, there is no truly effective treatment for this disease.
This research was funded by grants from a Canadian research chair, the Canadian Institutes of Health Research, the Canadian Foundation for Innovation, the Canadian Brain Research Fund, the Alzheimer Society of Canada, and the Fonds de recherche du Qu茅bec 鈥� Sant茅.
The article entitled 鈥淧roximity to parental symptom onset and amyloid burden in sporadic Alzheimer鈥檚 disease鈥� was published in JAMA Neurology on February 26, 2018. DOI:10.1001/jamaneurol.2017.5135
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