Mental health disorders could be a driving factor in heart-related deaths. (© pixelheadphoto - stock.adobe.com)
LONDON — Men at high risk for heart disease may also face an even more concerning issue — swiftly declining brain health. A new study finds men with risk factors for heart disease, such as obesity, are more likely to experience a decline in brain health 10 years earlier than women. The brain areas most affected include regions in charge of processing auditory information, emotional processing, and memory.
The study, published in the Journal of Neurology Neurosurgery & Psychiatry, showed declining brain health regardless of whether or not people carry the APOE ε4 gene — a major risk factor for Alzheimer’s disease.
Many variables that raise a person’s chances of developing heart disease are also risk factors for dementia. This includes having Type 2 diabetes, obesity, high blood pressure, and being a chronic smoker.
One question researchers have had is when is the best time to intervene and prevent declining brain health? Additionally, is there a difference in how cognitive decline develops in men and women?
Researchers collected data on 34,425 people from the UK Biobank who had both abdominal and brain scans. The average age for participants was 63, but the participants’ ages ranged from 45 to 82. The risk of heart disease was calculated by measuring a person’s age, blood fats, and systolic blood pressure — the first number of a blood pressure reading which reveals the maximum arterial pressure applied when the heart contracts and pumps blood. Additionally, researchers looked at whether people had blood pressure medication, were smokers, or had diabetes.
Looking at the brain scans, the researchers studied changes in brain structure and volume using a neuroimaging technique called Voxel-based morphometry. This tool helps measure how heart disease risk, abdominal fat, and the fat surrounding body organs affect neurodegeneration.
Results show high amounts of both fat types were linked to lower grey matter volume in the brains of men and women. Heart risk and obesity a decade earlier had more of an effect on declining brain health in men than in women.
Men with risk factors for heart disease were most at risk for brain damage between the ages of 55 and 74. For women at high risk for heart disease, these effects were seen between ages 65 and 74.
The results were seen as a bell-shaped curve over time, where high heart disease risk and obesity led to gradual loss of brain volume over multiple decades. The brain damage was less seen in people under 55 and those 75 and older, although the researchers state that this observation might be because fewer participants in those age groups were part of the study.
This relationship between heart disease risk factors and declining brain health remained regardless of whether people carried the APOE ε4 gene that makes someone more likely to develop dementia later in life. Researchers also observed that the temporal lobes were the brain areas most prone to damage. This region processes auditory, visual, and emotional information and is also involved in memory.
“The detrimental impact of cardiovascular risk was widespread throughout cortical regions, highlighting how cardiovascular risk can impair a range of cognitive functions,” the researchers say in a media release. “This highlights the importance of aggressively targeting cardiovascular risk factors before the age of 55 years to prevent neurodegeneration and Alzheimer’s disease, in addition to the benefit of preventing other cardiovascular events, such as myocardial infarction [heart attack] and stroke.”
According to the authors, one way people may be able to maintain good health is to use treatments for obesity and Type 2 diabetes for Alzheimer’s disease as well.
“Targeting cardiovascular risk and obesity a decade earlier in males than females may be imperative for potential candidates to achieve a therapeutic benefit in preventing neurodegeneration and cognitive decline,” the study authors conclude.
Although the findings are concerning, the researchers note that the brain normally declines because of aging. This includes atrophy of the temporal lobe, so it is difficult to tell whether heart disease risk factors are directly causing declines in brain health or if it results from normal aging. While not tested in the current study, the researchers have several explanations for why heart disease risk may be connected to declining brain health, such as increased inflammation, central leptin and insulin resistance, and disintegration of the blood-brain barrier.
Paper Summary
Methodology
The study investigated how cardiovascular risk factors and obesity affect brain health over time, using data from over 34,000 adults aged 45 to 82 years from the UK Biobank. Researchers analyzed brain scans (MRI) to measure grey matter volume — a marker of brain health. They assessed participants’ cardiovascular risk using the Framingham Risk Score, which considers factors like cholesterol, blood pressure, and smoking. To measure obesity, they used advanced imaging to calculate subcutaneous and visceral fat levels. The goal was to track changes in brain volume across different age groups and explore how genetics (APOE ε4 status) influenced these relationships.
Key Results
The study found that cardiovascular risk and obesity lead to brain shrinkage, particularly in areas like the temporal and frontal lobes. For men, the most significant impact occurred between ages 55 and 64, while for women, it happened a decade later, between 65 and 74. These changes were observed regardless of whether participants carried the APOE ε4 gene, which is linked to Alzheimer’s disease. The findings highlight a “bell-shaped” curve, where the effects peak in middle age and diminish in older groups.
Study Limitations
The study couldn’t pinpoint whether the brain changes were due to specific diseases like Alzheimer’s or just general aging. Another limitation was the lack of direct biomarkers for Alzheimer’s, such as amyloid or tau levels. Additionally, the oldest age group had fewer participants, which may have skewed the findings. Finally, the study didn’t compare outcomes between different APOE genotypes.
Discussion & Takeaways
This research suggests that targeting cardiovascular risk factors like obesity earlier in life could help prevent brain damage and diseases like Alzheimer’s. For men, interventions should ideally start by age 55, while women might benefit most starting a decade later. The results reinforce the importance of maintaining heart health to protect brain health, emphasizing the need for early and aggressive treatment strategies.
Funding & Disclosures
The study was funded by the Imperial College London President’s PhD scholarship, with additional support from the Medical Research Council, Alzheimer’s Research UK, and other organizations. Lead study author Paul Edison has consulted for pharmaceutical companies like Roche and Pfizer. All participants gave informed consent, and ethical approval was obtained from the North West Multi-centre Research Ethics Committee. Data came from the UK Biobank, which provides health information for research in the public interest.
