People with type 2 diabetes have an increased risk of dementia, but lifestyle changes such as stopping smoking and following a healthy diet, together with adherence to treatment targets such as blood sugar control, may be able to lower that excess risk, according to new research being presented at the European Association for the Study of Diabetes (EASD), held online this year (27 Sept-1 Oct).
By analysing brain scans and medical information from nearly 88,000 volunteers (over 10,000 with type 2 diabetes and more than 77,000 controls, average age 57 years) in the UK Biobank database over an average of 9 years, researchers found that the risk of dementia was progressively lower in individuals with type 2 diabetes who had a higher number of risk factors within guideline-recommended target levels (eg, not smoking, a healthy weight, and recommended levels of blood sugar and blood pressure), compared to controls without diabetes—with a 20% lower dementia risk for each additional risk factor within the target range.
Additionally, differences in cognitive performance and structural brain abnormalities were also progressively smaller with greater adherence to these targets. The results were replicated in the Maastricht Study—an independent population-based cohort from the Netherlands.
Maintaining recommended levels of blood sugar, being a non-smoker, and the absence of albuminuria (a sign of kidney damage) appeared to be the strongest risk reducers.
The study is the first to investigate the links between such a broad range of risk factors and the risk of dementia, and presence of cognitive dysfunction and structural brain abnormalities in type 2 diabetes.
“Our findings support current risk factor treatment strategies and making lifestyle changes ”, says co-lead lead author Dr April van Gennip from Maastricht University Medical Centre in the Netherlands. “These risk factors don’t just have an impact on the risk of developing dementia—they also have an impact on brain structure and current levels of cognitive function. Moreover, they are modifiable, making them important prevention targets.”
Type 2 diabetes is not only associated with an increased risk of dementia, but also a greater risk of cognitive dysfunction and structural changes in the brain that are important risk factors for dementia. This progressive disease can start to develop 15 to 20 years before any symptoms appear, so identifying factors that might prevent the onset of dementia are important. However, the extent to which taking steps to modify risk factors in type 2 diabetes can help reduce the risk of cognitive decline is unclear.
To provide more evidence, researchers examined the incidence of dementia, and presence of cognitive dysfunction (lower performance in tasks that evaluate processing speed, memory, and the ability to control behaviour, known as executive function) and structural brain abnormalities (ie, white matter hyperintensities and total brain volume). They looked at whether these associations differed according to the number of risk factors on target (ie, not smoking, and guideline-recommended levels of blood sugar, blood pressure, body mass index, albuminuria, physical activity, and diet). The researchers adjusted the results to account for confounding factors such as age, sex, and educational attainment. After an average follow-up of 9 years, 147 (1.4%) individuals with diabetes and 412 (0.5%) controls developed dementia.
The researchers found that when individuals with diabetes had 5 to 7 risk factors within the recommended target range, the excess risk of dementia associated with type 2 diabetes was substantially lower. Similarly, differences in processing speed, executive function, and brain volumes were progressively smaller for a higher number of risk factors on target.
“While there’s still no cure or way to reverse the majority of dementia diseases, our findings suggests that there are ways for people with type 2 diabetes that can reduce their excess dementia risk”, says co-lead author Dr Thomas van Sloten from Maastricht University Medical Centre in the Netherlands. “What’s more, the changes people with type 2 diabetes can make to lower dementia risk and keep their brains healthy offer a myriad of health benefits.”
The authors acknowledge that their findings show observational associations rather than cause and effect, and, therefore, they were unable to do a complete comparison of the effect of treating risk factors because some individuals may have had a risk factor within target range without treatment. Additionally, the results on cognitive performance and structural brain abnormalities were based on cross-sectional data. Also, a part of the excess risk of dementia, worse cognitive performance and structural brain abnormalities remained unexplained after taking into account all risk factors, and this remaining association may be due to other factors that the researchers did not address. Finally, they note that the study included mostly middle-aged Caucasian individuals, so the findings cannot be generalised to other ages or ethnic groups.
Diabetes Care
The authors declare no conflicts of interest.