Do patients with Parkinson's disease (PD) experience loss of appetite or weight?

Weight Loss and Appetite Changes in Parkinson's Disease

Yes, patients with Parkinson's disease commonly experience weight loss and decreased appetite as the disease progresses. Weight loss is a key feature of Parkinson's disease (PD) and meta-analysis confirms that PD patients have significantly lower BMI than healthy controls 1.

Prevalence and Timing of Weight Changes

• Weight loss may be present at diagnosis and is associated with disease progression 1
• Approximately 15% of community-dwelling PD patients are malnourished, with another 24% at medium or high risk of malnutrition 1
• Weight changes can occur throughout the disease course, with weight loss becoming more prominent as the disease advances 1

Mechanisms of Weight Loss and Appetite Changes

Increased Energy Expenditure

• Increased energy expenditure due to rigidity, tremor, and dyskinesias is a major contributor to weight loss 1, 2
• This increased expenditure is often not compensated by increased energy intake 1

Gastrointestinal Dysfunction

• Dysphagia affects 60-80% of patients, particularly in advanced disease 1
• Impaired gastrointestinal motility and gastroparesis affect nutrient intake 1, 2
• Constipation (14.2%) and dry mouth (13.4%) are among the most common symptoms affecting food intake 3

Medication-Related Factors

• Levodopa therapy is associated with side effects that can impact appetite and weight, including:
  • Nausea, vomiting, anorexia, and gastrointestinal disorders 4, 1
  • Dry mouth, taste alterations, and dyspepsia 4
• Higher levodopa doses (especially >6 mg/kg) are associated with greater risk of weight loss 1, 5
• Levodopa may enhance glucose metabolism, resulting in increased energy expenditure 2

Non-Motor Symptoms

• Depression, anxiety, and cognitive impairment can reduce appetite 1
• Loss of smell (olfaction) is associated with weight loss and may be part of an "olfaction-weight-dyskinesia phenotype" 5
• Fatigue, which affects up to 60% of PD patients, contributes to weight loss 6

Clinical Implications and Monitoring

• Weight loss is not benign and requires monitoring and intervention 1

• Malnutrition is associated with:

  • Increased disease severity 1
  • Higher mortality risk 5
  • Increased risk of developing levodopa-induced dyskinesias 5
  • Reduced quality of life 6, 5

• Regular monitoring recommendations:

  • Body weight should be monitored throughout disease progression 1
  • Nutritional assessment should be conducted at least yearly and whenever clinical conditions change 1
  • Vitamin status (particularly vitamin D, B12, and folate) should be regularly assessed 1

Management Considerations

• Levodopa dosing may need adjustment based on weight changes 1, 5
• Patients with lower body weight may require lower absolute doses of levodopa to prevent dyskinesias 5
• Attention to nutrition impact symptoms (NIS) is essential, as malnourished PD patients report significantly more symptoms affecting food intake (mean 3.4 symptoms vs 0.1 in well-nourished patients) 3
• Swallowing problems should be assessed and addressed, as they strongly correlate with malnutrition risk 3

Pitfalls and Caveats

• Weight gain can occur in early disease stages with dopaminergic treatment or after deep brain stimulation (DBS) 1
• Patients undergoing DBS should be monitored as weight gain is mainly fat mass accumulating in the abdominal region, potentially increasing metabolic syndrome risk 1
• Simply increasing levodopa dose without adjusting for weight loss can increase risk of dyskinesias 5
• Unconventional nutritional therapies that some PD patients pursue may exacerbate malnutrition 7