Hearing the word dementia has a devastating effect on those who have had a family member suffer with it. What is dementia and can it be prevented? Dementia isn’t a specific disease, but an umbrella term for a set of symptoms that affects memory, thinking, personality, and activities of daily living.  In addition, there is confusion, disorientation, and difficulty in finding words and problem solving.  Alzheimer’s disease is the most common cause of dementia, occurring in two thirds of all cases.  Vascular dementia is the second most common type, occurring as a result of damage to the blood supply to the brain. This damage may be from a stroke, diabetes or high blood pressure, putting heart patients at risk.  While dementia is not a normal part of aging, the older we get, the higher the risk for dementia.  Genetics play a big part; those with a family history of dementia are at higher risk. Other risk factors include, heavy alcohol use, smoking, high blood pressure, depression and diabetes. 

Mild cognitive impairment is an intermediate stage, where there are changes in thinking that exceed normal aging (benign forgetfulness), but not as severe as full-blown dementia (malignant forgetfulness).  One passes through the mild cognitive impairment stage on the way to dementia. 

Neither mild cognitive impairment nor dementia can be cured. There are many medications which help with the symptoms, but they don’t alter the course of the disease. Can dementia be prevented?  There are many over the counter products being sold that claim to prevent dementia. These include supplements, vitamins, ginkgo biloba, jellyfish proteins, green tea extract, St John’s wort and others. However, when rigorously tested, none of these compounds have been shown to slow the progression to dementia, despite their advertising claims. In February 2019, the Food and Drug Administration cracked down on the sale of unapproved products claiming to prevent, treat or cure Alzheimer’s disease sending warning letters to 17 companies selling these supplements.  Since this approach doesn’t work, what can prevent dementia? In 2017, a National Academy of Sciences panel reviewed all of the published prevention studies and suggested three interventions to slow cognitive decline: increased physical activity, blood pressure control and being mentally active. 

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Controlling high blood pressure as a measure to prevent dementia is an appealing concept.  The brain seems to be very vulnerable to sustained high blood pressure. Hypertension changes the structure of the small blood vessels of the brain, leading to vascular dementia. In addition, hypertension is a well-known risk factor for stroke. Can lowering blood pressure reduce the stress on the blood vessels and delay the progression of dementia? This hypothesis was tested in two large trials. In the HOPE trial, lowering blood pressure did not delay cognitive decline. This trial only included patients older than 70 years old. The SPRINT trial enrolled 9000 hypertensive patients with an average age of 68 and followed them for five years.  The risk for dementia was not reduced by intense blood pressure lowering (a blood pressure goal less than120) compared to a blood pressure goal less than 140.  However, the intense treatment group had a lower risk for mild cognitive impairment.  Unfortunately neither trial was able to prove that lowering blood pressure prevented dementia, but there are signals that we may be on the right path.  Both trials may be limited as the patients were older and followed for only a few years. Perhaps patients have to be followed for many years to see an effect and perhaps blood pressure control should start at an earlier age (for example, starting medications when patients are in their 40s). 

Thousands of studies have been conducted looking at exercise and brain function. In general, exercise is felt to be beneficial.  Exercise may be helpful in a variety of ways including lowering blood pressure and promoting neurogenesis (the generation of new brain cells).  A large recent study evaluated all of the clinical trials on exercise and brain function and concluded the following. Exercise significantly improved cognitive function in adults over 50 years old, even if mild cognitive impairment or dementia were already present. Since some patients may begin to show signs of dementia as early as 45 years old, it is never too early or too late to start exercising.  Aerobic exercise and resistance training were similarly effective. To achieve improvement in cognitive function, exercising for a minimum of 45 minutes at moderate to vigorous intensity, on as many days of the week as possible is recommended.

There is a lot we don’t know about preventing dementia. We do know that taking brain supplements and substances found in jellyfish do not work. Lowering blood pressure may be helpful but even if it isn’t, there is no downside. Controlling blood pressure is always beneficial for overall health and there is little risk. Similarly, exercise may or may not help prevent dementia but it is good for overall health and there are no side effects. So skip the supplements and walk away from dementia.