Diabetes and Alzheimer’s: Could overeating lead to dementia?

The number of people suffering from diabetes is on the rise. This rise runs alongside a worldwide increase in obesity, with around 10 percent of the population suffering from diabetes, and 12 percent considered obese.

Although we know bad eating habits increase our risk of developing diabetes, this doesn’t seem to be enough to make us ditch the junk! I know, despite having diabetes run in my family, that when the stress piles up I always crave comfort foods. But new research might soon encourage me to change these eating habits. Yes, if a long term risk of heart disease, blindness and nerve damage aren’t enough to make me snack less, the looming threat of Alzheimer’s may just do the trick.

Numerous studies have shown that people with type 2 diabetes are twice as likely to develop Alzheimer’s than the rest of the population. But why?

Alzheimer’s is a pretty complicated problem. In fact a confident diagnosis can still only be made following post-mortem. We know that in the late stages of the disease the brain is shrunken and riddled with clusters of mismanaged proteins called plaques and tangles. But what we don’t really understand is why these proteins start to misbehave in the first place.

The emerging picture is of a complex patchwork of many factors: all of which can initiate a downward cascade toward Alzheimer’s disease. Now, diabetes seems to be forming another patch on this causation quilt.

Type 2 diabetes, the kind that can develop later in life, is brought about by a number of factors: including obesity. This leads to an imbalance in insulin production. In non-diabetics insulin is produced at constant levels, causing cells around the body to absorb glucose from the blood; a process which is necessary for regulating carbohydrate and fat metabolism. Insulin can also cross into the brain and has been found to aid cognitive function.

Although it may seem counter-intuitive, the chronic high levels of blood insulin seen in many diabetics actually means less insulin crosses into the brain. This, combined with fluctuations in blood sugar, may explain why a number of diabetics report reduced cognitive function. But this is not the end of the story. Diabetes also has an effect on the metabolism of fat, leading to an overproduction of ceramides. These ‘waxy fats’ are released into the blood and cross into the brain. Once there, they cause brain insulin resistance and encourage inflammation.

It is believed that this mixture of insulin resistance and inflammation causes Alzheimer’s related proteins to collect in the brain and form plaques. In fact, scientists have recently discovered that inducing insulin resistance in the brains of mice and rats leads to both memory loss and accumulation of plaques.

This research certainly seems compelling, although within the scientific community the jury is still out on the exact role diabetes plays in the development of Alzheimer’s. I personally doubt that diabetes alone can be hailed as a causative factor for Alzheimer’s. However, if we connect the dots the two certainly seem to be linked, perhaps through overconsumption of fatty/sugary junk foods? Whatever the outcome, I know that this research will certainly make me think twice before reaching for the snacks in future!

Post by: Sarah Fox