Are you finding it hard to resist the craving to bite into that extra slice of cheese pizza or guzzle down another can of aerated sugar drink at your office party? If you are above 40 with a history of high blood glucose, then you should probably give it a miss.
That’s because multiple research studies indicate that if you are a middle-aged diabetic with poor blood glucose management and a host to its co-morbidities – mainly obesity and cardiovascular complications – then you could be at a higher risk of developing cognitive impairment, including dementia, in your twilight years.
The Institute of Health Metrics and Evaluation (IHME) at the University of Washington has, in its report titled ‘Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050’, listed high blood glucose as one of the high-risk factors that will lead to a surge in global dementia cases in the coming years.
The research analysis paper was published as part of IHME’s Global Burden of Disease (GBD) study funded by the Bill and Melinda Gates Foundation. Many countries make use of the GBD report to finalise future health policies. The Lancet’s Public Health journal published the IHME’s dementia forecast report in January 2022.
While interacting with Happiest Health, Emma Nichols, Master of Public Health, Researcher from the IHME research unit at University of Washington, pointed out multiple neurological and vascular scenarios in which uncontrolled high blood glucose levels could lead to cognitive impairments.
“A number of mechanisms have been proposed, including links through increased vascular damage and vascular brain pathology, changes in neuronal insulin resistance and signalling and promotion of a pro-inflammatory state,” Nichols said when asked about the link between glucose levels and cognitive impairment. Nichols is the lead author of the research team that compiled and brought out the IHME GBD dementia forecast report.
Apart from high blood glucose, the report includes obesity, smoking, lack of awareness and education along with other factors like air pollution as modifiable risk factors for dementia after studying individual and community level exposures to each of them. The report was based on data compiled and analysed from 204 countries.
“For example, improvements in global education access are projected to reduce dementia prevalence by 6.2 million cases worldwide by 2050. But this will be countered by anticipated trends in obesity, high blood sugar and smoking which are expected to result in an additional 6.8 million dementia cases,” the report says.
Science and warning signs
Earlier, the Lancet Commission listed middle-aged diabetics with sedentary lifestyle as high-risk category individuals likely to develop dementia in its ‘Dementia prevention, intervention and care’ report in 2017 and 2020. A study published in the 2017 September edition of Alzheimer’s and Dementia journal indicated that mid-life obesity linked with type 2 diabetes had a direct bearing on dementia in later years.
It has also claimed that majority of the individuals diagnosed with dementia were obese in their middle age. The excess weight along with insulin resistance put them in the high-risk category. Ironically, these obese middle-aged individuals started to lose weight soon after the onset of dementia – probably in a span of 10 years because of the cognitive shortcomings directly affecting their daily routine, diet patterns and other physical activities.
Another study, conducted by a research team from Sweden and published in Alzheimer’s and Dementia in 2021, also concluded that diabetes and poor glucose control along with cardiovascular complications could lead to a higher risk of developing or intensifying cognitive impairments. The study was based on a population study conducted on senior citizens.
Most of the research work undertaken to find the link between diabetes and dementia has listed cardiovascular complications triggering insulin resistance leading to inflammation as the main cause of concern. Internal inflammation that gets triggered as a series of chemical changes in the blood and vascular system snowballs into an unhealthy avalanche, disrupting neurological functioning of the brain. This can often lead to the person losing control of their cognitive capabilities.
Decoding diabetes and dementia
According to researchers, millions of nerve endings within our body constantly transmit, receive and process countless neurological signals every minute. This complex yet meticulous process is responsible for conceiving and co-ordinating our cognitive and physical actions.
These nerve endings have an outer protective covering called the myelin sheath. It is made up of protein and fatty acids, and allows the nerves to transmit and relay its signals to and from the brain. Excess glucose in the bloodstream adversely interacts with this sheath and corrodes its protein covering thereby disrupting or slowing down the transmission of neurological signals directly affecting the cognitive decisions.
Excess glucose in the blood stream could also impair neural functions altering vascular dynamics in the brain. It is also pointed out that if the individual is suffering from cardiac complications affecting blood supply to various parts of the body, then it could adversely affect the blood flow into the brain (cerebral blood flow). This will disrupt the blood-brain barrier that acts like a check dam blocking toxic chemicals in blood from flowing into the brain.
Connection between diabetes and dementia
As part of their efforts to understand and possibly pull out a dementia cure from their lab coat pockets, scientists are now focusing on finding the link between the hippocampus and hypothalamus of our brain. The hippocampus, the nerve centre of learning and reason, is responsible for controlling a major part of the brain’s cognitive functioning, whereas the hypothalamus gland is the hormone system controlling our impulsive and emotional responses including appetite, metabolism, desire, addiction, etc.
Since dementia affects the hippocampus whereas diabetes is concerned with the hypothalamus region, various studies are being conducted to examine the link between diabetes and dementia to figure out if there is a possible connection between the functioning of the hippocampus and the hypothalamus that would lead to a better understanding of both conditions.
“Further studies are required and are being carried out to fully understand the link between diabetes and dementia. There is also a proposal from a section of the medical and research community to classify Alzheimer’s as Type-3 diabetes,” says Dr Tom Babu, medical director, consultant diabetologist and endocrinologist, Silverline Hospital, Kochi, Kerala. He also pointed out recent research on how amyloid plaques could adversely affect neurological functioning, especially in the case of diabetics with high blood glucose levels.
Amyloid plaques are excess protein that gets deposited in spaces between nerve cells and form a plaque-like structure affecting the normal functioning of the neurons at the tip by disrupting their signal transmission to each other. Amyloid plaques are found in large numbers in the brain of people affected with dementia. Research is also under way since it is believed that some of the drugs used for diabetes control could be used against these plaques which could eventually establish a strong link between diabetes and Alzheimer’s dementia as far as treatment protocols are concerned.
Meanwhile Emma Nichols told Happiest Health that both individual and policy level changes were important when it came to addressing modifiable risk factors for dementia like high blood glucose, smoking and obesity.
“At an individual level, medical doctors can encourage patients to stay healthy, eat well and exercise. Policymakers can also address risk factors through bans or taxes on tobacco products or sugar-sweetened beverages. Policies around education reforms and reducing air pollution can also help to reduce the community-level exposures to risk factors.”
Low blood sugar and senior citizens with dementia
A few studies conducted on elderly people with diabetes and those already affected with advanced stage dementia, including Alzheimer’s, call for caution to ensure safe blood glucose levels, especially if they are already on diabetic medication. It has been pointed out that often people with diabetic dementia symptoms tend to skip regular meals, which could lead to extremely low blood glucose level and health complications in the absence of proper supervision.
“Complimentary risk factors, especially vascular ones like diabetes and heart issues, are always given priority when it comes to ensuring proper care for the elderly affected with Alzheimer’s and other forms of cognitive impairments. They often tend to forget after eating their meals and end up eating again, which might seriously affect their health.
Same goes in the case of medication: they might forget or take extra pills because of their cognitive limitations. So there has to be strict and gentle supervision from caregivers,” says Amrita Patil Pimpale, founder, Echoing Healthy Ageing, a Mumbai-based support group for senior citizens affected with dementia and their caregivers.
A study by the University of California San Francisco has pointed out that senior citizens with diabetic dementia might not be able to adhere to the strict medications and diet restrictions associated with diabetes management by themselves. After the publication of the study in JAMA Internal Medicine journal in 2013, the university said in a media release that these elderly people might not be able to recognize the symptoms of severe low blood glucose and respond accordingly on their own and in a timely manner.
Back to the future
As per the 2021 data from the International Diabetes Federation, there are at least 537 million diabetics across the world and the figure is expected to soar to about 783 million by 2045. India accounts for one in seven of all adults living with diabetes worldwide.
According to IHME the number of dementia cases worldwide is expected to go up from at least 57.4 million in 2019 to 152.8 million in 2050. India is expected to have at least 11.4 million dementia cases by 2050, a 197 per cent increase from 2019.