Lisa M. Shulman, MD, FAAN, responds:

Weight loss is fairly common in people with Parkinson's disease, although the reason for it is unknown. In most cases patients report losing weight in spite of a robust appetite (unlike your brother's loss of appetite) and using high-calorie supplements.

Confirm a Connection

The first step in managing the problem would be to confirm that your brother's weight loss is associated with PD. Losing weight can be connected to many medical conditions, so it's important to encourage your brother to see a primary care physician for a thorough evaluation to exclude other causes and factors.

Rule Out Depression

In addition to various medical conditions that can cause weight loss, emotional problems such as depression can also be contributing factors. Depression occurs in about one-third of PD patients. If depression is the problem, suggest that your brother see a therapist or psychiatrist, who will determine if he needs a prescription for an antidepressant. Depression in PD is treated with many of the same medications prescribed for the general population of people with depression.

Consult a Nutritionist

If your brother's doctor doesn't identify any other causes for his weight loss, you may want to consult a nutritional specialist who can review your brother's diet and suggest modifications, including high-calorie supplements.

Ask About Sense of Smell and Taste

If your brother has lost his sense of smell or taste, which is common in PD, that could also account for his weight loss and lack of appetite. For more information about this phenomenon and for tips and recipes that can help improve the appeal of food, take a look at Navigating Smell and Taste Disorders, a book published through the Neurology Now™ Books Series.