Cognitive ability and physical health predict dementia later in life

The risk of developing dementia later in life is strongly predicted by a person’s cognitive ability, functional limitations and physical health as many as 20 years before onset of the illness, according to a new RAND report.

Related new research found that early detection of cognitive impairment helps people to take mitigating actions to prepare for future loss of financial and physical independence. 

While older adults’ take-up of cognitive testing currently is low, additional research found that use of cognitive tests would increase if it was free and readily accessible, and with the development of improved treatments.  

Early detection of Alzheimer’s disease and related dementias among the 58 million Americans over 65 is critical, in part because available disease-modifying treatments only work for patients with early-stage disease. Only about 16% of people aged 65 or older take such an assessment during a routine visit with their primary care practitioner.

RAND researchers conducted three studies to understand who is most at risk for developing cognitive impairment, how to increase take-up of cognitive testing by older adults, and how to encourage at-risk individuals to continue receiving care for brain health.

The first study used data from cognition and dementia measures in the Health and Retirement Study to detect elevated risk for dementia years before its onset. The study is a nationally representative sample of about 20,000 older adults and their households in the U.S. that has been ongoing since 1992.

Lifestyle factors such as a lack of exercise, being obese  and not engaging in hobbies at age 60 were predictors of who would develop dementia, according to the analysis that examined 181 potential risk factors to see which were most associated with developing dementia.

In addition to lifestyle factors, researchers found regional associations with dementia. People born in the South face statistically significantly higher chances of developing dementia, even when controlling for many other factors.

Although Black, Hispanic and lower-income individuals had a higher risk of developing dementia, race and ethnicity were not risk factors after controlling for education and income. Parental health, family size and marital history  were not strong predictors of dementia. 

“This work provides additional evidence about actions that individuals can take to pursue a lifestyle that promotes brain health across the lifespan,” said Peter Hudomiet, the report’s lead author and a senior economist at RAND, a nonprofit research organization. “Understanding risk factors can enable health care providers and policymakers to identify groups at the highest risk so they can direct resources to delay cognitive decline or address its effects.”

To better understand what people do upon learning of potential cognitive impairment, a second study examined the relationship between individuals’ cognitive status, the mitigating actions they took to prepare for the effects of cognitive decline and how they subsequently fared. This analysis also used information from the Health and Retirement Study.

Researchers found that individuals who received a new dementia diagnosis were more likely to take action, with 25% seeking help with finances from their children, compared with only 2% of respondents without a diagnosis.

Even before receiving a medical diagnosis, people identified by survey measures as having dementia were much more likely to get help with finances -- 29% versus 2% among those with no dementia. This finding suggests that many individuals realize they have a cognitive issue and take actions before being clinically diagnosed. 

“When people receive a dementia diagnosis, they are more likely to take actions such as establishing a living will or power of attorney or move in with an adult child in order to receive help and reduce financial responsibilities,” said Michael D. Hurd, the study’s lead author and a senior principal economist.

In a third study, researchers surveyed a representative sample of Americans using the RAND American Life Panel and found that out-of-pocket costs were the strongest barrier to seeking cognitive assessments, follow-up appointments and dementia treatments.

If testing were free, 80% of respondents said they would undergo a cognitive assessment and 77% would take an early-detection test for Alzheimer’s. However, if testing cost $300, those willing to undergo testing dropped by about half.

Respondents indicated they would be most compelled to seek clinical care if it would lead to better treatment. About 60% said they would opt for a disease-modifying therapy if it would help them maintain independence for an additional three years.

“Broadening the use of cognitive assessments is an important strategy to identify patients who may benefit from current and future treatments for Alzheimer’s and related dementias,” said Susann Rohwedder, lead author of the third report and a senior economist at RAND. “Assessments provided individuals with information that may facilitate actions to prepare for the future.”

Support for the research was provided by Genentech.

The studies are available at www.rand.org. They are “Identifying Early Predictors of Cognitive Impairment and Dementia in a Large Nationally Representative U.S. Sample,” “Benefits of Seeking Early Detection of Cognitive Decline in the Absence of Treatment,” and “Individuals' Interest in Cognitive Screening, Dementia Diagnosis, and Treatment: New Estimates from a Population-Representative Sample.”

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