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Weight loss in Parkinson’s Disease

True story

I can never forget a 65-year-old Parkinson’s patient who came to my clinic, and said, “Dr. Chew, I have lost a lot of weight over the past six weeks. I can feel some lumps on my stomach. I think I have cancer of the stomach.”

True enough, I discovered some lumps on his stomach during the physical examination. I ordered some blood tests and arranged for an urgent CT scan abdomen for him. Two weeks later, I received the CT scan of the abdomen, which confirmed the patient’s suspicion: cancer of the stomach which had spread to the liver.

He was admitted to the ward on the same day to be managed by the cancer specialist. However, he declined cancer treatment and died three months later.


Weight loss is quite a common problem among Parkinson’s patients. It has been reported that Parkinson’s patients are four times more likely to loss more than 10 pounds of body weight compared with healthy people of the same age (Beyer PL, et al, 1995). Parkinson’s patients also have a higher risk of suffering from poor nutrition, weight loss and loss of muscle tissue compare with healthy people (Beyer PL, et al, 1995; Nutt JG, Carter JH, 1990).

Why do Parkinson’s patients lose weight?

The following are the reasons why a Parkinson’s patient can suffer from weight loss:

a) The illness (Parkinson’s Disease / PD) itself.

The tremor and dyskinesia (involuntary “dancing” movement due to levodopa) in PD themselves can cause weight loss, as they lead to prolonged muscle contraction which is similar to physical exercise. Furthermore, the slowness of movement itself, when severe, is enough to make it difficult for someone to walk to the kitchen to get food.

Management: The tremor can be reduced by optimizing the PD medications (increasing the dose or frequency of medications, or adding a new medication). Dyskinesia is more difficult to treat – brain surgery is generally the most effective treatment.

b) Dentition / Swallowing difficulty

Anyone who has difficulty biting due to poor dentition certainly cannot eat enough food, especially meats which contain protein (needed to maintain muscle tissue).

Difficulty in swallowing, which occurs in up to 40% of Parkinson’s patients, is usually mild to moderate in severity. It is commonly present when the effect of levodopa has worn off (“off period”), and improves soon after a dose of levodopa is taken. In addition to weight loss, difficulty in swallowing may lead to lung infection, as the food or liquid may enter the airways instead of going into the stomach.

Management: consult a dental surgeon for proper dentures, optimizing the PD medications as for tremor in (a).

c) Poor dietary habit

Those who consume improper choice of food (junk food) or inadequate meals may end up losing weight.

Management: consult a dietitian who can advise on the proper quantity and choice of daily food intake.

d) Depression

As up to 40-60% of Parkinson’s patients suffer from depression, it is an important and common cause of weight loss. However, as mentioned above, it is pertinent to exclude other conditions such as cancer before concluding that the cause of weight loss is depression. Thus, Parkinson’s patients with weight loss and depression should consult both physicians (or neurologists) and psychiatrists.

Management: medications (anti-depressants), counseling, moral support.

e) Cancer

As most Parkinson’s patients are elderly people, and the risk of developing cancer increases with age, cancer should be seriously considered when a Parkinson’s patient loses weight. Any growth in the stomach or intestine leads to loss of appetite and weight. Other symptoms which are suggestive of underlying cancer are constipation, blood in the stool and abdominal pain. Rarely, some patients notice the lumps on the stomach (as described in the beginning of this article), which indicate that the cancer is already at the advanced stage.

Management: consult the physicians (or neurologists), who will carry out investigations such as CT scans of internal organs. When confirmed, patients will be referred to the cancer specialist and surgeon.

f) Other medical disorders

Diabetes and thyroid gland disorders can cause weight loss. Blood tests are needed to confirm the presence of these disorders.


Parkinson’s patients who have weight loss should consult physicians or neurologists so that proper investigations (such as CT scans) are carried out to detect serious conditions such as cancer. The management of weight loss is actually a team-work that includes physicians, neurologists, dental surgeons, psychiatrists and dietitians.


  1. Beyer PL, Palarino MY, Michalek D, Busenbark K, et al. Weight change and body composition in patients with Parkinson’s Disease. J Am Diet Assoc 1995; 95: 979-983.
  2. Nutt JG, Carter JH. Dietary issues in the treatment of Parkinson’s Disease. In: Koller WC, Paulson G, eds. Therapy of Parkinson’s Disease. New York: Marcel Dekker, 1990: 531-553.