How Type-2 diabetes increases the risk of strokes, dementia

It is well-known that Type-2 diabetes increases the risk for heart disease but researchers now suggest that it can independently also increase the risk for dementia – a group of conditions that lead to impairment of the ability to remember, make decisions and social interactions. But there are ways to improve the outcome.
A recently published study in the journal Neurology showed that diabetics who followed seven health habits were less likely to get dementia.
The habits included no current smoking, moderate alcohol consumption – one drink a day for women and two for men – moderate physical activity for 2.5 hours a week or vigorous activity for 75 minutes, seven to nine hours of sleep daily, a healthy diet with more fruits, vegetables, and whole grains, watching less television, and having frequent social interaction.
What happens if you follow the seven healthy habits?
Researchers from Sweden and China followed over 1.67 lakh people, who were 60 years or older from the UK Biobank cohort for over 12 years and found that the diabetics who followed two or less of these seven healthy habits were four times (which translates to 400 per cent) more likely to get dementia than people without diabetes who followed all seven habits.
In comparison, diabetics who followed all the seven habits were only at a 74 per cent increased risk of dementia as compared to those without diabetes who followed all the seven habits.

Study author Yingli Lu from Shanghai Jiao Tong University School of Medicine in China, in a release, said, “We investigated whether a broad combination of healthy lifestyle habits could offset that dementia risk and found that people with diabetes, who incorporated seven healthy lifestyle habits, had a lower risk of dementia than people with diabetes who did not lead healthy lives.”
The study found that in diabetics who followed all the habits, the prevalence of dementia was 0.28 per cent (based on person-year, a measure for the number of people and amount of time they spent in the study). Among diabetics who followed only two or fewer habits, it was 0.69 per cent.

The author added, “Doctors and other medical professionals who treat people with diabetes should consider recommending lifestyle changes to their patients. Such changes may not only improve overall health but also contribute to prevention or delayed onset of dementia in people with diabetes.”
Dr Rajinder K Dhamija, a neurolog and director of Institute of Human Behaviour and Allied Sciences (IHBAS), said, “This is to be expected. Diabetes is a major risk factor for all vascular diseases, including strokes in the brain. One of the four major types of dementia is vascular dementia, accounting for about 20 to 25 per cent of all dementia cases, that is a result of repeated small strokes. So, if a person adopts a healthy lifestyle, they will reduce the chances of such complications of diabetes.”
He added, “Other than that, habits such as consuming good food and taking adequate rest also result in a healthier body and a healthier brain, there reducing the risk for the other forms of dementia as well.”
How does diabetes affect the brain?
A Havard Medicine write-up explains that one of the reasons is diabetes increases the risk of stroke, which in turn increases the risk of dementia. “However, strokes do not appear to be the complete answer as some studies found that diabetes led to an increased risk of dementia even when strokes were controlled for,” it said.
Another reason appears to be hypoglycaemia or low blood sugar episodes that occur in diabetics, especially those who tightly control sugar levels. Low blood sugar levels are known to damage the hippocampus, which is the memory centre of the brain.

The write-up also states that there are hypotheses that suggest diabetes could directly be leading to Alzheimer’s, the most common form of dementia. This is because insulin (the hormone that controls blood sugar levels) plays a critical role in formation of amyloid plaques – a naturally occurring protein that clumps together to form plaques between neurons – a dinguishing feature of Alzheimer’s.
What happens if you get diabetes early on?
A 2019 study published in Journal of the American Medical Association (JAMA) shows that the earlier the onset of diabetes, greater the risk of dementia. The study found 8.9 cases of dementia for every 1,000 people in those without diabetes at age 70. “Comparable rates of dementia for those with diabetes were 10.0 for those with onset up to five years earlier, 13.0 for six to 10 years earlier, and 18.3 for more than 10 years earlier,” according to the Harvard medicine write-up.