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The Onset of Alzheimer’s: The Importance of Family History

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Alzheimer's

Summary:

Researchers report the closer a person gets to the age their parents started to develop Alzheimer’s symptoms, the more likely they are to have amyloid plaques.

Article Body:

You’re about to turn 60, and you’re fretting. Your mother has had Alzheimer’s 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’s, 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’Ouest-de-l’Île-de-Montréal) shows that the difference between a person’s 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’s 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,” explains Villeneuve, an assistant professor at McGill University and a core faculty member at the McConnell Brain Imaging Centre at the Montreal Neurological Institute and Hospital (The Neuro).

Her team of scientists also found that the genetic impact of Alzheimer’s disease is much greater than previously thought.

“Upon 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 ‘Alzheimer’s gene’,” 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’s disease. According to the Alzheimer Society of Canada, 564,000 Canadians currently have Alzheimer’s 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.

About this neuroscience research article

Funding: 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 Québec — Santé.

Source: Bruno Geoffroy – McGill University
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract in JAMA Neurology.
doi:10.1001/jamaneurol.2017.5135

Cite This NeuroscienceNews.com Article

McGill University “The Onset of Alzheimer’s:The Importance of Family History.” NeuroscienceNews. NeuroscienceNews, 27 February 2018.
< http://neurosciencenews.com/family-history-alzheimers-onset-8566/>.

Abstract

Proximity to Parental Symptom Onset and Amyloid-β Burden in Sporadic Alzheimer Disease

Importance Alzheimer disease (AD) develops during several decades. Presymptomatic individuals might be the best candidates for clinical trials, but their identification is challenging because they have no symptoms.

Objective To assess whether a sporadic parental estimated years to symptom onset calculation could be used to identify information about amyloid-β (Aβ) levels in asymptomatic individuals with a parental history of AD dementia.

Design, Setting, and Participants This cohort study analyzed Aβ1-42 in cerebrospinal fluid (CSF) specimens from 101 cognitively normal individuals who had a lumbar puncture as part of the Presymptomatic Evaluation of Novel or Experimental Treatments for Alzheimer Disease (PREVENT-AD) cohort from September 1, 2011, through November 30, 2016 (374 participants were enrolled in the cohort during this period). The study estimated each participant’s proximity to his/her parent’s symptom onset by subtracting the index relative’s onset age from his/her current age. The association between proximity to parental symptom onset and Aβ levels was then assessed using apolipoprotein E ε4 (APOE4) status and sex as interactive terms. These analyses were performed again in 2 independent cohorts using CSF and Pittsburgh compound B carbon 11–labeled positron emission tomography (PIB-PET) Aβ biomarkers: the Adult Children Study (ACS) and the Wisconsin Registry for Alzheimer Prevention (WRAP) cohorts.

Main Outcomes and Measures The association between proximity to parental symptom onset and Aβ burden in asymptomatic individuals with a parental history of sporadic AD.

Results The present analysis included a subset of 101 PREVENT-AD individuals (mean [SD] age, 61.8 [5.1] years; 30 [29.7%] male), 128 ACS participants (112 participants underwent CSF measurement: mean [SD] age, 63.4 [5.1] years; 31 [27.7%] male; and 107 underwent PIB-PET: mean [SD] age, 64.6 [5.3] years; 27 [25.2%] male), and 135 WRAP participants (85 participants underwent CSF measurement: mean [SD] age, 59.9 [6.0] years; 27 [31.8%] male; and 135 underwent PIB-PET: mean [SD] age, 59.6 [6.1] years; 43 [31.9%] male). In the PREVENT-AD cohort, individuals approaching their parent’s onset age had lower CSF Aβ1-42 levels (range, 402-1597; B = −9.09, P = .04). This association was stronger in APOE4 carriers (B = −17.9, P = .03) and women (B = −19.8, P = .02). In the ACS cohort, the main association was replicated using PIB-PET data, and the sex interaction was replicated using CSF and PIB-PET data. In the WRAP cohort, the results were not replicated using cross-sectional data, but the main association and the APOE interaction were replicated using PIB-PET longitudinal data.

Conclusions and Relevance These results suggest that proximity to parental symptom onset may help estimate Aβ biomarker changes in women or APOE4 carrier asymptomatic individuals with a parental history of sporadic AD.

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