There's A New Theory About Alzheimer's Risk—And It Involves Sugar

A team of neurologists, neuroscientists, and experts on fructose metabolism conducted the research. The evidence not only points to the link between excess sugar and cognitive decline, but it also helps explain the association between metabolic health and Alzheimer's. 

Some background: What exactly is "fructose metabolism"?

There are two common types of sugars: fructose and glucose. 

Fructose is a natural sugar, commonly found in fruit, fruit juices, and honey. But it also makes up 50% of most table sugars, meaning it can be present in processed foods, sodas, baked goods, and high-fructose corn syrup—pretty much anything with added sugars2. 

Glucose, on the other hand, is a type of simple sugar that's less sweet than fructose. When it travels to the bloodstream, it becomes what we commonly know of as blood sugar.

A 2017 Yale study found that when people have elevated blood sugar levels for hours at a time, the brain starts to overproduce fructose. This mechanism is called fructose metabolism and is common in type 2 diabetics. 

How does this impact Alzheimer's risk?

When fructose metabolism occurs due to excess sugar consumption, the brain essentially goes into overdrive. The process of neural glycolysis uses up necessary cerebral energy, making brain neurons less functional or viable over time, study author Richard Johnson, M.D., explains in a news release.

"In essence, we propose that Alzheimer's disease is a modern disease driven by changes in dietary lifestyle in which fructose can disrupt cerebral metabolism and neuronal function," his study states. 

The research suggests excess consumption of fructose can increase fructose metabolism in the brain. The process ultimately takes energy away from other, more necessary, brain functions. Over time, this may lead to the development of Alzheimer's disease—though more research needs to be done to confirm the theory. 

"By outlining consistent evidence, we're hoping to inspire researchers to continue exploring the relationship between fructose in the brain and Alzheimer's disease," Johnson says. "New treatments aimed at inhibiting intracerebral fructose metabolism could provide a novel way to prevent and treat this disease." 

In the meantime? Cutting back on sugar (sorry, sweet. tooths) may be one way to stave off these unwanted neurodegenerative effects. Other lifestyle habits, like regular exercise, staying positive, and even drinking coffee can also help support the brain.