DEMENTIA IS A CATCH-ALL TERM FOR LOSS OF MEMORY, problem-solving, memory, and other thinking abilities. These deficits interfere with activities of daily living, with Alzheimer’s disease being the most common form of dementia.

Alzheimer’s dementia is not a normal part of the aging process. Still, the most significant risk factor is increasing age, with most of those with Alzheimer’s disease 65 years and older.

For those who get it at a younger age, we refer to it as early-onset Alzheimer’s disease. These younger folks can be in the condition’s early, middle, or late stages.

We may conveniently divide Alzheimer’s disease into two forms:

• Common Alzheimer’s disease. Those with early-onset Alzheimer’s disease have the common form. It progresses similar to AD seen in older adults.
• Genetic (familial) Alzheimer’s disease. This type of AD is uncommon. Symptoms typically emerge while individuals are in their 30s, 40s, or 50s. Family history is the only known risk factor for genetic (familial) Alzheimer’s disease.

Dementia is the product of brain cell damage, with this injury interfering with brain cells’ communicating with one another. Without good inter-nerve cell chatting, behavior and feelings can change.

Dementia: A global public health epidemic

Dementia is a global health issue of increasing importance. There are tremendous negative consequences for numerous socioeconomic measures (and the burden on sufferers).

By 2030, over 82 million people — and over 150 million by 2050 — will have Alzheimer’s dementia. Unfortunately, there are no curative treatments, and we don’t understand why the disease occurs.

For those without the less common genetic form, why does dementia happen? Researchers are examining shared genetics with other diseases to understand better the biological mechanisms underlying Alzheimer’s disease.

A new study adds support for a brain-gut connection.

The gut-dementia connection

Family history is the only known risk factor for Alzheimer’s dementia. We have to do better in identifying causes. Now comes an innovative study connecting the gut microbiome to the brain and dementia risk.

Several studies demonstrate the co-occurrence of dementia (especially Alzheimer’s) with gut disorders such as gastritis, the gut microbiome, and certain medicines (such as proton pump inhibitors) used to treat peptic ulcer disease.

Gut-brain axis

While such studies suggest an association between Alzheimer’s and gastrointestinal tract disorders, it is unclear whether the gut issues are risk factors for dementia or vice-versa. The gut-brain axis exists for other central nervous system problems such as Parkinson’s disease and depression.

Today we examine an Australian study that comprehensively analyzes the link between Alzheimer’s disease and gut disorders. While we will learn that they could not find a causal relationship between dementia and the gastrointestinal tract, they did find shared genes and enrichment of autoimmunity and more.

The gut, the brain, genetics, and dementia

The research investigation incorporated data from historical genome-wide association studies. They looked for patients with Alzheimer’s dementia, gastroesophageal reflux disease (heartburn), peptic ulcer disease, irritable bowel syndrome, inflammation of the stomach and small intestine (gastritis-duodenitis).

The final group analysis represented more than 450,000 individuals. Here are the results:

All the gastrointestinal tract disorders (except irritable bowel syndrome) appeared to correlate with Alzheimer’s dementia.

Among the biological factors examined, abnormal cholesterol appeared to underscore the gut-brain connection. Abnormal cholesterol appeared to be a risk factor for gut disorders and Alzheimer’s dementia.

The study authors suggest that cholesterol-lowering statin drugs (such as atorvastatin or lovastatin) be studied to see if they help protect the gut and, in turn, the brain.

My take — The gut, brain, and dementia

Of course, correlation is not causality: We don’t have evidence that gut disorders cause Alzheimer’s or vice-versa. Still, the researchers point to a Mediterranean-type diet — one rich in natural fats and vegetables — as not a bad idea.

The researchers report no relevant financial relationships. Thank you for joining me in this look at the relationship between the gut and Alzheimer’s dementia.