Summary: Researchers reveal people may be developing Alzheimer’s later in life and living less time with the neurodegenerative disease.
Source: UT San Antonio.
The diagnosis is one that a family never wants to hear: Your father has Alzheimer’s disease. Your mother has stroke-related dementia.
A recently released study, included in a special supplement to the Journal of Gerontology, indicates that dementia’s impact might be compressing a bit. That is, people might be developing dementia later and living with it for a shorter period of time.
Sudha Seshadri, M.D., professor of neurology and founding director of the Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases at UT Health San Antonio, is the senior author on the study, which draws evidence from the Framingham Heart Study.
In data from four different time periods over a period of 30 years, the mean age at dementia onset increased, while the length of time living with dementia decreased. Is it because prevention and care of stroke today is superior compared to decades ago? Stroke is a major risk factor for dementia.
“Prevention of stroke and reduced impact of stroke are great advances, but neither completely explains the trend we are seeing,” Dr. Seshadri said. “We are looking at other causes, such as lower burden of multiple infections because of vaccination, and possibly lower levels of lead or other pollutants in the atmosphere. Early education and nutrition might also play a role.”
Stroke risk has decreased because of greater control of blood pressure. Dr. Seshadri again cited Framingham data: “In the past, if you had a stroke you were at 90 percent greater risk to develop dementia. Today, you have a 40 percent greater risk,” she said.
Source: Will Sansom – UT San Antonio
Publisher: Organized by NeuroscienceNews.com.
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Original Research: Abstract for “Are Trends in Dementia Incidence Associated With Compression in Morbidity? Evidence From The Framingham Heart Study” by Carole Dufouil, PhD Alexa Beiser, PhD Geneviève Chêne, MD, PhD Sudha Seshadri, MD in Journal of Gerontology. Published April 16 2018.
Are Trends in Dementia Incidence Associated With Compression in Morbidity? Evidence From The Framingham Heart Study
Several epidemiological studies suggest declining trends in dementia over the last three decades with both decreasing age-specific prevalence and incidence. There is limited data on whether this delayed clinical onset is accompanied by a shorter postdiagnosis survival.
A total of 5,205 participants from the Framingham Original and Offspring cohorts were studied. Four epochs were considered from 1977–1984 to 2004–2008. Gender and education adjusted 5-year mortality risks were estimated using delayed entry Cox models with the earliest epoch as reference category. Stratified analyses by sex, education, and age were undertaken. A nested case control study of 317 dementia cases and 317 controls matched on age, gender and epoch was initiated.
In the whole sample, 5-year mortality risk has decreased with time, it was 33% lower in the last epoch compared to the earliest. In the 317 persons who developed dementia, age at onset increased (1.5 years/epoch), and years alive with dementia decreased (1 year/epoch) over time. We observed however, a decreased adjusted relative mortality risk (by 18%) in persons with dementia in 1986–1991 compared to 1977–1983 and no significant change from then to the latest epoch. The nested case control study suggested in matched controls that 5-year mortality relative risk had increased by 60% in the last epoch compared to Epoch 1.
In the FHS, in the last 30 years, disease duration in persons with dementia has decreased. However, age-adjusted mortality risk has slightly decreased after 1977–1983. Consequences of such trends on dementia prevalence should be investigated.