Healthy aging and brain function

Jane Graham, RD

Tel: (613) 316-7780; e-mail: [email protected]

Jane is a Registered Dietitian in private practice at the Riverside South Medical Centre. She specializes in chronic disease management, diabetes, gastro-intestinal disorders, plant-based diets, food allergies and/or intolerances.

An estimated 500,000 Canadians have Alzheimer’s disease or a related dementia. That includes one in four people over the age of 85. Most survive for four to eight years after they’re diagnosed, much of that time in a nursing home or in the care of family members at home.
Needless to say, researchers are scrambling to find measures to prevent, or even delay, dementia.
So far, no one has found a magic bullet to stop Alzheimer’s disease, which gums up the brain with protein clumps and tangles. But Alzheimer’s isn’t the only cause of dementia.
Damage to the brain’s blood vessels – often due to high blood pressure, smoking or diabetes – can also play a role, not just in dementia, but in milder memory loss as well.
When arteries become stiffened, narrowed and tortuous, it is much harder for brain blood flow to occur normally. That can lead to a stroke that is obvious, or to one that is never noticed. It’s estimated that 20 percent of older people have had a so-called silent stroke, and don’t even know it. Over time, repeated injury to the brain’s blood vessels can lead to mild cognitive impairment (MCI), and people with MCI often go on to develop dementia.

Here are some lifestyle approaches to keep your brain and those of your loved ones in good working order for as long as possible:

Monitor blood pressure – There is a wealth of evidence that high blood pressure is a risk factor for late-life cognitive impairment. The good news: blood pressure can be controlled with diet, exercise, weight loss, and, if necessary, medication.

Control blood sugar and insulin – There is no question that diabetes damages blood vessels. Research now suggests that it may also shrink parts of the brain. A recent study reported in Diabetes Care found more brain atrophy in 350 people with diabetes than in 363 people without the disease.
Further, it’s not just those with diabetes who are at risk. People who have what doctors call “metabolic syndrome” also have a higher risk of cognitive decline. This group has higher than normal blood sugar levels (but not high enough to be classified as diabetes), often in combination with high blood pressure and cholesterol. And they may have high blood insulin levels because obesity – especially an oversized waist – has made them insulin resistant.
High insulin in the body means lower insulin in the brain. That’s because, over time, high levels of insulin in the blood may shrink the number of receptors for insulin in the blood-brain barrier, allowing less to enter the brain.
This is cause for concern because recent research funded by the U.S. National Institutes of Health suggests that insulin may protect brain function by clearing toxic beta-amyloid protein plaques out of the brain, a known contributing factor to Alzheimer’s.
The key to lowering blood sugar and insulin in the blood – and presumably raising insulin in the brain – is to lose excess weight and exercise more.

Get moving – Several studies have found a lower risk of dementia in people who exercise or are lifelong exercisers versus those who don’t. How might exercise protect the brain? One theory is based on microscopic blood vessels. If you are sedentary, blood won’t get to the far reaches of those small vessels. These are the areas that support the kind of executive function that is vulnerable to aging. In animals, exercise causes these small vessels to grow and expand their reach.

Use it or lose it – Cognitive reserve – that’s what researchers call a lifetime’s worth of exercising your brain. Many studies find a lower risk of dementia in people with more education and literacy,  in professional or managerial occupations, and who are more involved in mentally stimulating activities (like reading, playing games or attending classes). While cognitive reserve may not offer complete protection against brain disease, it may delay the onset of symptoms.

What to eat – To keep a lid on blood pressure and blood sugar, eat a diet based on the OmniHeart and DASH studies.
DASH stands for “Dietary Approaches to Stop Hypertension”. Like the Mediterranean diet, the DASH diet promotes a diet high in vegetables and fruit, whole grains, fish, poultry, low fat dairy, nuts, seeds and legumes. It is low in red meat, sweets and added sugars.
The OmniHeart Trial examined three different versions of the DASH diet, each with differing amounts of macronutrients: one higher in carbohydrate, one higher in protein and one higher in unsaturated fats.  All three diets found improvements in blood pressure, LDL cholesterol and triglycerides, however, the diets higher in protein and unsaturated fats saw better results than the diet high in carbohydrate.
Following the DASH or the OmniHeart regimen results in a diet high in potassium, magnesium, calcium and fibre which, in combination, are associated with numerous health benefits.

Don’t rely on vitamin supplements – Vitamin supplements don’t compensate for a bad diet. Period.
How food, and its component molecules, affect the body is largely a mystery. That makes the use of supplements for anything other than treating a deficiency questionable.
Studies examining B vitamins, anti-oxidant vitamins (C, E, beta-carotene) and multi-vitamins showed no benefit relative to cognitive function. In fact, some studies have linked high doses of anti-oxidant vitamins to increased risk of lung and prostate cancer.
Nutrition research is now starting to move away from nutrient focused studies to look at whole foods since most of us don’t consume nutrients but we eat food.
Rather than thinking too much about individual nutrients, choose whole, unprocessed, healthful foods that include the full orchestra of nutrients, rather than lone notes of a single vitamin or mineral.

In conclusion, while genetics play a critical role in the development of Alzheimer’s and dementia, new and evolving research confirms that diet and lifestyle may delay the onset and mitigate the severity of symptoms.