Brain scans of 9,772 people aged 44 to 79, who were enrolled in the UK Biobank study, have revealed that smoking, high blood pressure, high pulse pressure, diabetes, and high BMI — but not high cholesterol — were all linked to greater brain shrinkage, less grey matter and less healthy white matter.
Smoking, high blood pressure, and diabetes were the most important factors, but there was also a compound effect, with the number of vascular risk factors being associated with greater damage to the brain. On average, those with the highest vascular risk had nearly 3% less volume of grey matter, and one-and-a-half times the damage to their white matter, compared to people who had the lowest risk.
The brain regions affected were mainly those involved in ‘higher-order’ thinking, and those known to be affected early in the development of dementia.
The associations were as strong for middle-aged adults as for older ones, suggesting the importance of tackling these factors early.
While the effect size was small, the findings emphasize how vulnerable the brain is to vascular factors even in relatively healthy adults. This also suggests the potential of lifestyle changes for fighting cognitive decline.
Although this study didn't itself examine cognitive performance in its participants, other studies have shown links between cognitive impairment and vascular risk factors, particularly diabetes, obesity, hypertension, and smoking.
Cognitive decline in type 2 diabetes linked to white matter hyperintensities
While type 2 diabetes has been associated with cognitive problems, the mechanism has been unclear. Now a study involving 93 people with type 2 diabetes has found that greater white matter hyperintensities (indicative of cerebral small vessel disease) were associated with decreased processing speed (but not with memory or executive function).