We typically associate insulin resistance with obesity and type 2 diabetes, but insulin resistance is also a significant risk factor for dementia and Alzheimer’s.
Insulin resistance in the brain promotes chronic, low-grade inflammation, cellular dysfunction, and impaired mitochondrial function, all contributing to neuronal damage and cognitive impairment.
In fact, some researchers refer to Alzheimer’s as “type 3 diabetes.”
Promotion of beta-amyloid plaques
Insulin resistance exacerbates the accumulation of beta-amyloid plaques in the brain, a key pathological feature of Alzheimer’s disease. Beta-amyloid oligomers, clumps of beta-amyloid precursors to plaques, bind to hippocampal neurons. This reduces insulin sensitivity in the hippocampus, the area crucial for memory formation.
These oligomers also activate inflammatory pathways, further inhibiting insulin signaling.
Abnormal phosphorylation of tau protein
Studies show a correlation between insulin resistance and the abnormal phosphorylation of tau protein, another hallmark of Alzheimer’s disease. Tau proteins help transport nutrients and other compounds throughout the brain, but this system breaks down under abnormal phosphorylation.
Abnormal tau phosphorylation affects the brain’s ability to form new neuron connections essential for memory and cognitive function. The result is impaired cognition and worsening memory.
Dietary and lifestyle factors in preventing Alzheimer’s
The primary contributors to insulin resistance are a diet high in sugars, junk foods, unhealthy fats, processed carbs, and a sedentary lifestyle. In other words, the standard American diet.
The diet you should follow depends on many factors, and there is no one diet for all. However, your diet should stabilize your blood sugar and promote insulin sensitivity.
Healthy fats like olive and avocado oil, omega-3 fatty acids, high-fiber foods, and low-glycemic foods have been shown to decrease the risk of neurodegeneration. A good example is a grain-free version of the Mediterranean diet that emphasizes vegetables, fruits, healthy fats, and fish consumption.
A whole-food ketogenic diet has also been shown to be neuroprotective.
Lifestyle risk factors for Alzheimer’s and dementia include certain medications like benzodiazepines, sleep aids, anticholinergic drugs, and others.
Smoking, inadequate sleep, high body mass index, a sedentary lifestyle, chronic stress, and chronic diseases like cardiovascular disorders are also significant risk factors for Alzheimer’s and dementia.
Reducing the risk of dementia and Alzheimer’s requires addressing multiple targets and pathways. This is why researchers have not yet found an effective Alzheimer’s drug despite tens of billions of dollars spent.
I explain these multiple factors in greater detail in my course, Cognitive Decline: Solving the Puzzle.
You can also learn more in my book, Why Isn’t My Brain Working?
Or, watch this video.