People with Parkinson’s disease who lose weight may be more likely to develop dementia and have a shorter lifespan, a new study suggests.

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Researchers suggest a high-calorie diet could help to offset the risks of weight loss in people with Parkinson’s.

Based on their results, study leader Dr. Angus Macleod — of the University of Aberdeen in the United Kingdom — and colleagues speculate that a high-calorie diet could help to increase the life expectancy of individuals with Parkinson’s disease.

The team’s results are published in the journal Neurology.

Parkinson’s disease is a neurological condition characterized by tremors, limb rigidity, and problems with balance and movement.

It is estimated that around 1 million people in the United States are living with Parkinson’s disease, and around 60,000 new cases are diagnosed in the country every year.

While a number of studies have shown that weight loss is common among people with Parkinson’s disease, Dr. Macleod and colleagues note that few studies have investigated how this weight loss might affect clinical outcomes.

To address this research gap, the team analyzed data from the Parkinsonism Incidence in North-East Scotland (PINE) study. This is a population-based cohort of individuals with Parkinson’s disease or atypical parkinsonism from Scotland, U.K.

Atypical parkinsonism is used to describe symptoms similar to those seen with Parkinson’s disease but which are caused by other conditions.

For their analysis, the researchers included 187 people with Parkinson’s disease and 88 people with atypical parkinsonism. These individuals were matched by age and sex with 240 controls, who were free of Parkinson’s disease or Parkinson’s-like symptoms.

Over a follow-up period of up to 10 years, the weight of each subject was assessed annually. For the purposes of the study, clinically significant weight loss during follow-up was defined as losing 5 percent or more of baseline body weight.

The team investigated how clinically significant weight loss affected three outcomes among the participants: dependency on carers, the onset of dementia, and mortality.

The study revealed that people with Parkinson’s disease and atypical parkinsonism were a lower weight at study baseline than controls, and they lost weight much more rapidly during follow-up.

“Weight loss was observed in all groups over time, but patients with PD [Parkinson’s disease] lost weight more rapidly than controls, and those with atypical parkinsonism lost weight most rapidly,” the researchers note.

What is more, the team found that early weight loss among individuals with Parkinson’s disease or atypical parkinsonism was independently associated with a 2.23-times increased risk of dementia and a 1.23-times greater risk of death.

Additionally, weight loss in the first year after a Parkinson’s or atypical parkinsonism diagnosis was associated with greater dependency on carers.

The researchers admit that there are some limitations to their study. For example, they note that some study participants required home visits because they were too frail to attend clinics. As such, these individuals may have already been at greater risk of weight loss and poorer clinical outcomes.

“This could have led to underestimation of differences between patients and controls and underestimation of the associations between weight loss and poor outcome,” the authors write.

The team notes that data on some potential confounders were also missing from the analysis, including nutritional status, use of medication, and possible external stressors.

These limitations aside, Dr. Macleod and his team believe that their study not only confirms previous research showing that weight loss is common among individuals with Parkinson’s disease, but it also demonstrates the potential risks of weight loss.

Furthermore, the researchers believe that certain lifestyle interventions — such as adopting a high-calorie diet — could help to reduce weight loss and the associated risks for people with Parkinson’s, though more research is needed to confirm this theory.

Our finding that those who lose weight have poorer outcomes is important because reversing weight loss may therefore improve outcomes. Therefore, it is vital that further research investigate whether […] high-calorie diets will improve outcomes in people with Parkinson’s who lose weight.”

Dr. Angus Macleod