The progression of Alzheimer's disease

Editor's note: CNN's Dr. Sanjay Gupta answers medical questions submitted by e-mail on "Your Health," which airs at 2:30 p.m. ET Saturdays. Questions and answers are posted on CNN.com after the show.

Q: What are the "stages" for Alzheimer's disease? -- Andrew Garcia from Albuquerque, New Mexico

A: Andrew, as you know, in Alzheimer's disease, nerve cells in the brain die, making it difficult for the brain's signals to be transmitted properly.

A person with Alzheimer's disease has problems with memory, judgment and thinking, which makes it hard for the person to work or take part in day-to-day life.

Most patients' symptoms progress slowly over a number of years.

The course of disease progression is defined by levels or periods of severity: early, mild, moderate, moderately severe and severe or late-stage.

For example, in early-stage Alzheimer's, an individual may experience mild to moderate cognitive impairments.

Patients with late-stage Alzheimer's have little capacity for self-care due to their dementia symptoms.

Q: What is the recommendation as the daily guideline for cholesterol intake? -- Cherie in Exeter, California

A: Good question, Cherie. Your body gets cholesterol from two sources: from the foods you eat and from your liver.

And it's your liver that actually produces up to 80 percent of what you need. The other 20 percent comes from food.

Furthermore, each person's body processes cholesterol differently. Some people who eat high-cholesterol diets have very high cholesterol levels; others may have normal or low levels.

Regardless, a healthy diet is usually the first step in lowering cholesterol.

The National Institutes of Health's national cholesterol education program came up with the Therapeutic Lifestyle Changes (TLC) Diet, which calls for less than 7 percent of your daily calories to come from saturated fat -- because it elevates cholesterol. It also recommends that you eat no more than 200 milligrams of dietary cholesterol per day.