Summary: Lifestyle may be more important than age in determining a person’s cognitive function and future dementia risks, a new study reports.
Individuals with no dementia risk factors, such as smoking, diabetes or hearing loss, have similar brain health as people who are 10 to 20 years younger than them, according to a new Baycrest study.
The study found that a single dementia risk factor could reduce cognition by the equivalent of up to three years of aging.
“Our results suggest lifestyle factors may be more important than age in determining someone’s level of cognitive functioning. This is great news, since there’s a lot you can do to modify these factors, such as managing diabetes, addressing hearing loss, and getting the support you need to quit smoking,” says Dr. Annalise LaPlume, Postdoctoral Fellow at Baycrest’s Rotman Research Institute (RRI) and the study’s lead author.
The study is one of the first to look at lifestyle risk factors for dementia across the entire lifespan.
“While most studies of this nature look at mid- and older-adulthood, we also included data from participants as young as 18, and we found that risk factors had a negative impact on cognitive performance across all ages. This is crucial as it means risk factors can and should be addressed as early as possible,” says Dr. Nicole Anderson, Senior Scientist at the RRI, Associate Scientific Director of Baycrest’s Kimel Family Centre for Brain Health and Wellness, and senior author of this study.
The study, published today in the journal Alzheimer’s & Dementia: Diagnosis, Assessment, and Disease Monitoring, a journal of the Alzheimer’s Association, included data from 22,117 people aged 18 to 89 who completed the Cogniciti Brain Health Assessment, developed by Baycrest. Participants took the test in their own homes by going to the Cogniciti website (https://cogniciti.com/). The test takes around 20 minutes to complete and consists of a background questionnaire and four cognitive tasks.
The researchers looked at participants’ performance on memory and attention tests, and how this was impacted by eight modifiable risk factors for dementia: low education (less than a high school diploma), hearing loss, traumatic brain injury, alcohol or substance abuse, hypertension, smoking (currently or in the past four years), diabetes and depression.
Each factor led to a decrease in cognitive performance by as much as three years of aging, with each additional factor contributing the same amount of decline. For example, having three risk factors could lead to a decrease in cognitive performance equivalent to as much as nine years of aging. The effects of the risk factors increased with age, as did the number of risk factors people had.
“All in all, our research shows that you have the power to decrease your risk of cognitive decline and dementia,” says Dr. LaPlume. “Start addressing any risk factors you have now, whether you’re 18 or 90, and you’ll support your brain health to help yourself age fearlessly.”
This research was supported by the Alzheimer Society of Canada, and the Natural Sciences and Engineering Research Council of Canada.
With additional funding, the researchers could look further into the differences between normal agers and “super agers” – people who have identical cognitive performance to those several decades younger than them.
The adverse effect of modifiable dementia risk factors on cognition amplifies across the adult lifespan
Reversible lifestyle behaviors (modifiable risk factors) can reduce dementia risk by 40%, but their prevalence and association with cognition throughout the adult lifespan is less well understood.
The associations between the number of modifiable risk factors for dementia (low education, hypertension, hearing loss, traumatic brain injury, alcohol or substance abuse, diabetes, smoking, and depression) and cognition were examined in an online sample (N = 22,117, ages 18–89).
Older adults (ages 66–89) had more risk factors than middle-aged (ages 45–65) and younger adults (ages 18–44). Polynomial regression revealed that each additional risk factor was associated with lower cognitive performance (equivalent to 3 years of aging), with a larger association as age increased. People with no risk factors in their forties to seventies showed similar cognitive performance to people 10 or 20 years younger with many risk factors.
Modifiable dementia risk factors amplify lifespan age differences in cognitive performance.