A new study has found that people with better cardiovascular health metrics scores in midlife had a significantly lower risk of late life dementia.
Dementia is a global health issue accompanied by a significant societal and financial burden. Although there are options that may help treat the symptoms, there is currently no cure or disease-modifying therapy.
More than 5 million adults aged 65 years and older in the United States are predicted to have dementia, with projected increases to nearly 14 million people by 2050.
Severe cognitive dysfunction involving difficulties with memory, recognition, language, decision making, attention, and problem solving accompanies dementia. This can interfere with a person’s daily functioning.
Some lifelong modifiable risk factors identified in epidemiological studies, including cardiovascular risk factors from mid to late life, play a crucial role in the onset and progression of dementia.
In fact, simulation research estimates that up to 35% of dementia cases may be due to modifiable risk factors across the life span. These risk factors include social and mental health factors such as education, social engagement, hearing loss, and depression.
Epidemiological studies also show the importance of cardiovascular health in the prevention of dementia. Factors such as smoking, diabetes, heart failure, atrial fibrillation, high blood pressure, obesity, and high cholesterol are all associated with an increased risk of dementia.
Studies suggest that optimal cardiovascular health metrics correlate with a decreased risk of stroke and coronary heart disease.
The American Heart Association’s (AHA) seven cardiovascular health metrics include four behavioral components:
- physical activity
- body weight
The other three components are biological:
- blood cholesterol
- blood pressure
- blood glucose
Scientists have associated having ideal cardiovascular health metrics in midlife with a reduced incidence of dementia in later life.
In the new study, midlife was a mean age of 50.4 years. However, one study with older participants (mean age of 67 years) found that ideal cardiovascular health metrics for the biological components of the AHA score decreased the risk of dementia 7 years later.
Until now, few studies have examined the relationship between cardiovascular health metrics from both mid and late life and the risk of dementia. They also have not analyzed the separate effects of the behavioral and biological components of the score.
Yajun Liang and colleagues conducted a population-based cohort study, involving 1,449 participants from the Finnish Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study, to fill this gap.
The study, which appears in the journal PLOS Medicine, analyzed data from people enrolled in the CAIDE study from 1972–1987 (midlife was a mean age of 50 years) to 1998 (late life was a mean age of 70 years). The team also followed 744 people without dementia in 2005–2008.
The cardiovascular health metrics the researchers measured included 6 of the 7 AHA recommendations. However, there were no dietary data, and fasting blood glucose measures in midlife were missing. For this reason, the researchers used a proxy measure of a diagnosis of diabetes.
They then subcategorized these metrics as behavioral (smoking, body mass index [BMI], and physical activity) or biological (total cholesterol, fasting plasma glucose, and blood pressure).
Their study collected data on demographics, lifestyles, medical histories, and other cardiovascular health metrics through clinical exams, laboratory tests, patient registers, a self-administered survey, and prescribed drug registers.
Diagnoses of dementia followed criteria specified in the Diagnostic and Statistical Manual of Mental Disorders. The study used the mini-mental state exam to assess cognitive functioning at follow-up in 1998 and 2005–2008.
The study defined ideal cardiovascular health metrics as:
- physical activity causing breathlessness and sweating more than twice per week
- a BMI of less than 25
- fasting plasma glucose levels of less than 100 milligrams per deciliter (mg/dl) without treatment in late life and no diabetes diagnosis or use of diabetes medication in midlife
- total serum cholesterol levels of less than 200 mg/dl
- a blood pressure of less than 120/80 millimeters of mercury (mm Hg) without needing to take blood pressure medication
- never smoking or having quit smoking for longer than 1 year
The study assessed and scored each of these cardiovascular health metrics alone and as a composite at both midlife and late life.
An additional 61 and 47 participants received a diagnosis of dementia in 1998 and 2005–2008, respectively.
The study found that participants with an ideal composite cardiovascular health metrics score in midlife had a 54% lower risk of dementia than participants with a poor score. This was after controlling for death and other potential confounding factors.
The results showed that a 1-point increase in composite cardiovascular health metrics score correlated with a 14% decrease in dementia risk.
Additionally, people with ideal behavioral cardiovascular health metrics scores in midlife had a 58% decrease in dementia risk. In contrast, people with ideal biological cardiovascular health metrics scores in late life had a 3.5 times higher risk of dementia.
The researchers conclude that having a blood pressure of less than 120/80 mm Hg and low total cholesterol levels might also be markers of preclinical dementia, thereby decreasing these metrics’ predictive values.
The study’s major limitations include the lack of data on diet and midlife glucose levels, high rates of loss to follow-up, and small subgroups limiting the power and generalizability of the study findings. They require confirmation in large-scale population-based studies.
However, this study does confirm earlier findings that suggest that the biological component of cardiovascular health is less predictive of dementia as people age. It also underlines the importance of ongoing behavioral cardiovascular health into older age.
The findings could have a substantial impact on the development of optimal risk mitigation strategies. Maintaining healthful cardiovascular health habits — particularly regarding smoking, physical activity, and BMI — may decrease dementia risk in late life, ultimately reducing the burden of this condition.