New research finds that some risk factors that affect the health of our blood vessels can also influence the health of our brains into old age.
It is no secret that the global population is aging at an increasingly fast pace. According to the World Health Organization (WHO), there were approximately 900 million people across the globe who were aged 60 and above in 2015. The WHO expect this number to jump to 2 billion by 2050.
According to the Population Reference Bureau, the number of seniors in the United States over the age of 65 may more than double from 46 million today to more than 98 million by 2060.
The burden of age-related chronic disease is also increasing. For instance, the Centers for Disease Control and Prevention (CDC) warn that the burden of Alzheimer's disease will double by 2060 when 13.9 million people in the U.S. will have the disease.
In this context, it is more important than ever to understand the mechanisms and risk factors behind age-related cognitive impairment.
Dr. Simon Cox, a senior research associate at the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh in the United Kingdom, led the new research.
Vascular risk tied with 'worse brain structure'
Cox and colleagues examined the brain scans of 9,772 people who were between 44 and 79 years old. They looked for any connections between the participants' brain structure and the following vascular risk factors: "smoking, hypertension, pulse pressure, diabetes, [high cholesterol], body mass index (BMI), and waist-hip ratio."
The study's senior author explains the methods used in the study, "We compared people with the most vascular risk factors with those who had none, matching them for head size, age, and sex."
The study found that all of these vascular risk factors — apart from high cholesterol — correlated with greater brain atrophy, less gray matter, and poor white matter health.
"We found that, on average, those with the highest vascular risk had around 18 [milliliters (ml)], or nearly 3 [percent], less volume of grey matter," reports the lead author, "and one-and-a-half times the damage to their white matter — the brain's connective tissue — compared to people who had the lowest risk; 18 ml is slightly more than a large tablespoon-full, or a bit less than a small, travel-sized toothpaste tube."
Gray matter is brain tissue located mostly on the surface of the brain that contains most of the neurons (nerve cells). White matter is tissue found deeper in the brain. White matter declines with age and previous studies have linked the loss of white matter integrity with "slower processing speed and poorer executive function."
The study's senior author further details the findings, saying, "We found that higher vascular risk is linked to worse brain structure, even in adults who were otherwise healthy."
"These links were just as strong for people in middle-age as they were for those in later life, and the addition of each risk factor increased the size of the association with worse brain health."
"Importantly," continues the researcher, "the associations between risk factors and brain health and structure were not evenly spread across the whole brain; rather, the areas affected were mainly those known to be linked to our more complex thinking skills and to those areas that show changes in dementia and 'typical' Alzheimer's disease."
Lifestyle changes may improve brain aging
Of all the vascular risk factors the team investigated, smoking, hypertension, and diabetes had the most consistent associations with changes in brain structure.
Because it is possible to modify some of these vascular risks, the findings point to lifestyle changes that could improve brain health and ensure healthy cognitive aging.
"Lifestyle factors are much easier to change than things like your genetic code — both of which seem to affect susceptibility to worse brain and cognitive aging. Because we found the associations were just as strong in mid-life as they were in later life, it suggests that addressing these factors early might mitigate future negative effects."
Dr. Simon Cox
"These findings might provide an additional motivation to improve vascular health beyond respiratory and cardiovascular benefits," concludes the researcher.