An estimated 387 million people worldwide had diabetes in 2014, and the incidence rate is expected to continue its rapid climb in the future, reaching 592 million by 2035. People with diabetes face numerous potential health complications including stroke, nerve damage, kidney disease and blindness. New research has added yet another potential complication to that list, dementia. Studies found that people with diabetes, particularly type 2 diabetes, have a higher risk of developing Alzheimer’s disease or other types of dementias.
The bottom line is that blood sugar and the brain are connected. Diabetes occurs when the body does not make enough insulin or does not effectively use the insulin it makes. Insulin is a hormone that controls glucose levels, or the amount of sugar, in the blood. Glucose is a main source of fuel for all cells in the body, including the brain.
Type 1 diabetes, which accounts for about ten percent of all cases, occurs when the pancreas does not produce adequate levels of insulin. This is the type usually diagnosed in children and adolescents, and is treated with insulin medication. With type 2 diabetes, the far more common form of the disease, the body’s cells stop taking in glucose from the bloodstream. It is either because the pancreas is not creating enough insulin, or the body has become insulin-resistant and cells are ignoring the insulin’s repeated requests to pick up glucose.
In cases of insulin resistance, the pancreas actually increases the production of insulin in an attempt to get cells to take up glucose. But the insulin-resistant cells don’t take in the necessary glucose for energy production and it accumulates in high levels in the blood; these high blood sugar levels go on to damage nerves and blood vessels. Also, when cells are insulin-resistant, they are starved of the glucose they need to function. Though glucose is there in ample supply in the blood, the cells just aren’t picking it up. This is how it works in the whole body, including the brain. Damaged blood vessels in the brain do not nourish brain cells effectively and so, cells die off and symptoms of dementia develop.
Blood sugar is not the only way diabetes impacts cognitive function. Diabetes is also known to be linked to strokes; one study found that midlife diabetes is associated with an 85 percent higher risk of micro-strokes in the brain. Other studies have shown that micro- strokes are linked to cognitive impairment. Yet another possible impact of diabetes on dementia was found in a study that discovered that a lack of insulin in the brain may be linked to the formation of protein-plaque that is associated with Alzheimer’s.
Highlights from research linking diabetes & cognitive decline
Other research looked at diabetes’ effects on less severe forms of brain dysfunction such as memory loss or mild cognitive impairment (MCI), a condition in which people experience a slight but
noticeable and measurable decline in memory or other thinking skills. Not surprisingly, it turns out that diabetes, or blood sugar irregularities in non-diabetics, appear to be linked to these milder forms of brain dysfunction.
Diabetes can accelerate aging of the brain.
After analyzing decades of health data from almost 16,000 people in the United States, researchers from Johns Hopkins Bloomberg School of Public Health found direct links between diabetes and cognitive decline. The data showed that having diabetes in middle age can “age” your brain approximately five years faster than normal, e.g., on average, a 60-year-old who has diabetes experiences cognitive decline on par with a 65-year-old who is aging normally.
Lower blood sugar may be good for your brain.
Even for people who don’t have diabetes or high blood sugar, those with higher blood sugar levels are more likely to have memory problems, according to a study published in October 2013 in the online issue of Neurology. Participants’ blood glucose levels and memory skills were tested; recalling fewer words on the memory test was associated with higher blood sugar levels. The same study measured the volume of each participant’s hippocampus and found that people with higher blood sugar levels also had smaller volumes in the hippocampus.
Women-specific research confirms link between diabetes and cognitive decline.
A study of 9,704 older women (average age, 72 years at baseline) published in the February 2007 edition of the Journal of the American Geriatrics Society examined participants’ cognitive function over a 15-year period. The strongest factor found to be associated with maintaining good cognitive function over time was lack of diabetes. Women who did not have diabetes were almost twice as likely to maintain strong cognitive function than women who did have diabetes.
Preventing Diabetes & Cognitive Decline
Alzheimer’s Disease International says, “The high prevalence of diabetes makes it potentially one of the most important modifiable risk factors for dementia.” It is so important because, as they pointed out, it is a modifiable risk factor. This means there are steps individuals, health professionals and governments can take to help lower incidence rates and prevent negative side effects.
An important first step is finding out if you have diabetes. The International Diabetes Federation estimates that 179 million people with diabetes are undiagnosed. The Canadian Diabetes Association website (www.diabetes.ca) shares a wealth of information about diabetes including a list of signs and symptoms to watch for and a description of the process for getting tested. There is much you can do to significantly reduce diabetes-related complications and mortality, but you can’t be proactive if you go undiagnosed.
If you don’t have diabetes, there are many things you can do to prevent it. It is estimated that over 50 percent of type 2 diabetes could be prevented or delayed through healthy lifestyle choices.
Whether you’ve been diagnosed with diabetes or not, the emerging link between diabetes and dementia provides a compelling reason to take steps to control your blood sugar. Everyone can benefit from the risk-reducing effects of a healthy diet and exercise, and those with diabetes may need to also use oral hypoglycaemic drugs or
insulin.
The link between diabetes and dementia helps dispel the myth that dementia is a disease that one gets completely by chance. Adopting a healthy lifestyle that controls your blood sugar levels can go a long way toward improving your odds of avoiding diabetes in all its forms, along with its complications, including cognitive decline and dementia.
Risk Score Predicts Danger of Dementia for Type 2 Diabetics
Although having diabetes almost doubles the risk of dementia, not all diabetics will develop dementia. Researchers at Kaiser Permanente and University Medical Centre Utrecht in the Netherlands created a tool to help predict which
type 2 diabetics have the highest future risk of developing dementia. They examined data over a 10-year period from nearly 30,000 older patients with type 2 diabetes, looking for factors that were most predictive of dementia. They used the eight factors they discovered to create the Diabetes-Specific Dementia Risk Score, a measure utilizing a 20-point scale to represent the risk of developing dementia over the next decade. Individuals who fall into the lowest category of risk score were found to have a 5.3 percent chance of developing dementia in the next 10 years, while people in the highest risk score category were found to have a 73 percent chance. Since all of the factors can be assessed easily, primarily based on medical history, the risk score can be calculated for an individual patient during a routine medical visit.
