Your instincts to encourage exercise for your forgetful father are good. Exercise is one of our best ways to prevent or slow memory loss.

Exercise can prevent dementia. A 2005 study observed almost 1450 people for about thirty years. The study showed that men and women who had regular exercise habits in mid-life are less likely to have dementia in their senior years.

In the study, being "active" meant having “leisure-time physical activity that lasts at least 20 to 30 minutes and causes breathlessness and sweating” at least twice per week. People who exercised in this way between ages 39 to 64 had less than half the risk of developing dementia in later years compared with adults who were not active.

People with the gene called apolipoprotein E4 (or “APO E4”) have a higher risk of developing Alzheimer’s. The study found they had an even stronger protection against developing Alzheimer’s by exercising. For every one person with this gene who exercises and gets Alzheimer’s, there are five people with this gene who are not active who get Alzheimer’s.

Exercise can also improve memory loss for people who are in the early stages of dementia. "Mild cognitive impairment" is the medical term for memory loss that cannot be attributed to normal aging, but is not severe enough to interfere with daily activities. Within a year, 10% to 15% of people who notice mild cognitive impairment will see their symptoms worsen and be diagnosed with dementia.

A study published this year showed that aerobic exercise can improve mild cognitive impairment. This was a small study of 33 adults with mild cognitive impairment. Some people did aerobic exercise while supervised by a trainer for 45 to 60 minutes per day, four days per week. Other people did gentle stretching exercises while supervised for the same amount of time, but this group kept their heart rate low. The study lasted for six months.

The people in the aerobic group did better on memory tests and tests of word-finding skill (fluency). The benefit was more noticeable in women than in men. The group that did gentle stretching did not improve their scores when they were retested.

Your father, who gets lost in his neighborhood, has a special situation. Exercise is not helpful unless it is safe. Getting lost is a problem that occurs in fairly advanced stages of dementia. Your father should not go on walks alone, because of his history of getting lost.

Good ways for him to continue to get exercise might include walking with a group, joining an adult day health program, or moving to a facility that provides supervised exercise.

Some families try to help in this situation by giving cell phones to their family member or even using global positioning system (GPS) devices. The value of these strategies has not been proven.