Cognitive reserve can protect you from the effects of Alzheimer's and other diseases that affect the brain.

Consider two older people with the same amount of Alzheimer's disease–related plaques and tangles in their brains. One person has some memory miscues now and then, but continues to lead a normal life. The other has the severe loss of memory and other cognitive deficits that come with Alzheimer's disease. Why the difference? One explanation is that they had differing amounts of cognitive reserve.

Cognitive reserve can be thought of as having two parts, hardware and software. The hardware consists of brain ...

1. Thyroid medicine People take levothyroxine (Levothroid, Synthroid, other brands), a synthetic version of thyroid hormone, when their thyroid glands don't produce enough of the hormone naturally. Many start taking thyroid medicine when they're relatively young, so by the time they're older, they've been on thyroid medicine for years, if not decades.

With age, the body's need for thyroid hormone decreases. So in many cases, if an older person sticks with the dose she took when she was younger, she may be taking too much thyroid medicine. Yet patients (and their doctors) often like the higher doses, because thyroid medicine ...

Moderate consumption of marijuana doesn't adversely affect lung function, according to a study.

A study published in 2012 in The Journal of the American Medical Association (JAMA) had some good news for people who smoke marijuana: smoking at a rate of one joint a day for as long as seven years doesn't seem to affect lung function adversely.

And then there was the really good news for pot smokers: smoking marijuana in moderation may actually improve lung function, perhaps because inhaling gives the lungs and the chest muscles a bit of a workout.

Comparisons to tobacco The JAMA report ...

Vigorous exercise may prevent Parkinson's disease and help treat it.

Parkinson's disease is a brain disease that affects the body and how it moves. Yet moving the body — that is to say, exercising — may be one of the best and most underutilized ways of combating the condition. Exercising vigorously when you're middle-aged may (sorry, no guarantees) lessen your chance of getting Parkinson's disease when you're older. And for people who already have the disease, exercise during the early stages — when a fair amount of physical movement is still possible — may slow the pace at which ...

Many studies have linked heart disease and depression, but heart problems may also go hand in hand with anxiety.

Several studies have shown that about a quarter of people with cardiovascular disease have some kind of anxiety problem and, in some cases, the anxiety seems to make the heart condition worse.

Researchers have reported, for example, that heart patients who have generalized anxiety disorder — constant, pervasive worrying, even about mundane matters — are more likely to have heart attacks and serious heart problems than heart patients who don't.

Panic attacks, which can be isolated or part of an anxiety ...

Are processed meats really that bad for you? What if I eat them only in small amounts?

Departures from the familiar yellow are often harmless but should be discussed with a doctor.

Most of the time, urine is a pale yellow color because it contains urochrome, one of the substances produced when hemoglobin gets broken down. Hemoglobin is the protein in red blood cells that sticks to oxygen so it can be ferried around the body.

Occasionally, though, urine turns a very different color. Men may notice the change as their urine enters the toilet bowl or urinal. Women may be more likely to observe it after wiping. Seeing red or orange instead of the usual yellow ...

Choline may labor in obscurity — if you haven't heard of it, you're in the majority — but it's an essential nutrient that does important work in the body.

And now there's some research that lends some credence to claims that the nutrient may be something of a "brain food" that fends off cognitive decline in old age.

Choline (pronounced KO-lean) plays a critical role in a wide variety of biochemical chain reactions, including some that are necessary for very basic functions, like keeping cell membranes intact. It and a more familiar vitamin, folate, share a nutritional teeter-totter: the less ...

I'm 80, I exercise and eat a healthy diet. My internist says my LDL is too low and that I should cut my statin from 40 mg to 20 mg a day. I also take 2,000 mg of niacin daily. Is there general agreement that one's LDL should not go below a certain point?

Is it true that you can get a tingling feeling from taking too much vitamin B6?