Stay sharp as you age

It is no secret that age and ­memory are intertwined. But age itself is not the sole reason that we forget things. Memory loss often can be traced to specific factors, including hormonal changes, inflammation and exposure to mercury and other toxins.

Common causes of memory loss—and what you can do to control them…

Low testosterone

After a man reaches age 30, his testosterone goes into free fall. Levels drop by about 1% a year. At least 30% of men in their 70s are hypogonadal, with very low testosterone.

Low testosterone increases the death of brain cells. It also has been linked to an increase in amyloid-B, proteins that are associated with Alzheimer’s disease and other forms of dementia.

What to do: If a saliva test shows low testosterone, your doctor may recommend creams, injections or other forms of testosterone replacement. Men who supplement with testosterone have been shown to have improvements in verbal memory (the recall of verbal information) and spatial memory (the part of the memory responsible for recording information about one’s environment and spatial orientation).

Important: Women need testosterone, too, and should get tested. Testosterone replacement in women with low levels can help preserve memory.

Low estrogen

Women often refer to the “brain fog” that occurs during menopause. It’s a real phenomenon that is caused in part by declining levels of estrogen. ­ Every brain cell is affected by estrogen, which conducts chemical signals through the hippocampus and other areas of the brain.

Low-dose estrogen replacement can improve brain circulation and reduce the risk for Alzheimer’s disease by up to 54%.

Men also depend on estrogen for brain function, although they require smaller amounts than women.

What to do: Both men and women should ask their doctors for a saliva-estrogen test. It measures “free” levels of the three different forms of estrogen (estrone, estradiol and ­estriol). Free estrogen is the form that is active and available for immediate use in the body.

If your estrogen is low, your doctor may prescribe supplemental hormones. I advise patients to use ­bioidentical hormones that are made from natural substances. They may be more effective—and cause fewer side effects—than synthetic forms of estrogen.

Low thyroid

People with low levels of thyroid hormone (hypothyroidism) often experience memory loss. Unfortunately, doctors don’t routinely test for it. They mistakenly attribute the symptoms—such as memory loss, fatigue, increased sensitivity to cold, apathy or weight gain—to other conditions, including depression.

What to do: Get a thyroid test if you have any of the above symptoms. A diet high in B vitamins (from meats, whole grains and fortified cereals) and ­vitamin A (from brightly colored ­produce) can help improve thyroid function. An adequate intake of iodine (iodized salt is a source) also is important.

If your level of thyroid hormones is too low, your doctor probably will prescribe a thyroid replacement, such as levothyroxine (Synthroid) or Armour Thyroid.

Impaired circulation

If you have high cholesterol or other cardiovascular risk factors—you smoke, have high blood pressure, are sedentary, overweight, etc.—you probably have at least some atherosclerosis, fatty plaques in the arteries that reduce the flow of blood and oxygen to the brain.

What to do: In addition to the obvious—more exercise, weight loss, not smoking—I strongly advise patients to eat a Mediterranean-style diet. This features lots of fruits, vegetables and grains along with healthy amounts of olive oil and fish. A recent study found that people who closely followed this diet were 28% less likely to develop mild cognitive impairment and 48% less likely to get Alzheimer’s disease.

Also helpful: Eating more soluble fiber (such as that found in oatmeal, beans, fruit and nuts) or taking a fiber supplement has been shown in both men and women to decrease hardening of the arteries and improve circulation.

Exposure to mercury

Americans are exposed to mercury all the time. It is present in soil, the water supply and some foods, including many fish. It also is used in many dental fillings. Over time, the mercury from fillings and other sources can cause inflammation and oxidative stress in the brain, both of which can damage the neurotransmitters that are essential for memory and other brain functions.

What to do: You can get tested for mercury and other heavy metals, but the tests will be positive only after long-term exposure. I advise patients to reduce their exposure long before it will show up on any test.

If you have dental fillings made of amalgam (an alloy of mercury and other metals), consider replacing them with fillings made from plastics or other materials. The work should be done by an environmental dentist who specializes in the safe removal of mercury.

Also important: Avoid eating shark, swordfish, king mackerel, marlin, ­orange roughy, ahi tuna and tilefish, which tend to accumulate mercury. Limit canned albacore tuna to three servings or less per month and canned light tuna to six servings or less per month. Best: Cold-water salmon.