Scientists Discover New Parkinson's Disease Symptom

Parkinson's disease has both motor and non-motor symptoms. Among the latter, a new one seems to have been certified by science.
Scientists Discover New Parkinson's Disease Symptom
Leonardo Biolatto

Written and verified by the doctor Leonardo Biolatto.

Last update: 08 March, 2023

Although it may seem that there couldn’t be any new Parkinson’s disease symptom left to discover, the truth is that many researchers are looking backwards. What do we mean by this? Simply that research is being carried out to identify possible early signs that would point to the onset of the disease or predict a slower evolution of the condition.

Finding a new Parkinson’s disease symptom, apart from what we know already, would be very useful. Doctors could then track risk factors and implement proactive measures to slow the onset of tremors, cognitive impairment, and speech disorders.

Recent research published in the prestigious journal Neurology seems to have hit the nail on the head. Scientists found that weight loss may precede cognitive decline and even predict it.

What was the research about?

The scientific study collected data from 358 participants. These were patients with newly diagnosed Parkinson’s disease who were closely followed for 8 years to monitor various aspects of their evolution.

After that time, and after analyzing the data backwards, the researchers had a surprise. Those who had lost significant weight in the first year after diagnosis progressed more rapidly toward reduced cognitive function.

The cutoff was set at 3%. That is, a 70-kilogram patient, for example, who lost more than 2.1 kilograms in the first year, showed earlier problems in cognition than the others in the group.

Conversely, those who gained weight early after diagnosis delayed the cognitive symptoms of Parkinson’s disease. And the cut-off point here was 3% (i.e. having gained at least that percentage in weight).

This new Parkinson’s-related symptom appears to be specific to cognitive, but not to motor signs. In the research, regardless of weight gained or lost, patients had the same evolution in their tremors, posture, and gait difficulties.

Parkinson's disease symptom.
Although tremors are the most well-known symptom in the general population, Parkinson’s affects other spheres of life

What do the findings mean?

The finding of a new Parkinson’s disease symptom which occurs early on is extremely relevant to clinical practice. Other researchers had already warned that the nutritional status of these patients can’t be avoided in the medical approach.

Beyond the fact that nutrition is important in any chronic disease, its role in neurodegenerative pathologies is increasingly understood and analyzed. From theories that postulate poor nutrition as a causal agent of cognitive impairment, to the more conservative ones that stipulate how weight variations are multifactorial in a patient with Alzheimer’s or Parkinson’s disease.

Up to half of the patients with Parkinson’s disease have significant weight variations during the development of the pathology. Why? This is partly explained by changes in lifestyle, difficulty in eating, depression that takes away hunger, and even the medication used for treatment.

However, all the intrinsic mechanisms of the process of weight loss or gain in neurodegenerative diseases are not clear. Feeding the patient correctly could make a difference. At least, that is one of the key points of the findings published in Neurology.

Although the new symptom associated with Parkinson’s is linked to cognitive impairment in the Neurology publication, there is some evidence that motor symptoms would also be affected. This was postulated by U.S. scientists in a 2016 publication.

According to the authors, patients with changes in body mass index (BMI) obtained differences in motor assessment tests used for Parkinson’s. This means that poor nutrition impairment is global for people with the pathology.

What should physicians do with this new symptom of Parkinson’s?

To establish weight loss as a new predictive symptom of cognitive impairment in Parkinson’s is to prompt physicians to monitor this factor in consultations. That is, weighing patients regularly to recognize the problem early.

These findings highlight the potential importance of weight control in the early stages of Parkinson’s disease.

~ Jin-Sun Jun, one of the authors of the Neurology study ~

Should this change protocols? The truth is that neurologists who see patients with the disease always weigh them. Nutrition is a common concern because, as we have already remarked, half of those affected lose weight in the first year after diagnosis.

What could change here is that those with some worrying signs, who don’t yet have a confirmed diagnosis of Parkinson’s, would have to be weighed. Perhaps, a steeply declining BMI sets the tone for advancing pathology certification.

So, the finding becomes relevant, not only for neurologists, but also for clinicians. Unfortunately, many neurodegenerative pathologies are diagnosed with delay. An early and well-defined sign would change the game in favor of early diagnosis.

A person weighing themselves.
Weighing patients with suspected Parkinson’s will become crucial in consultations.

Reducing diagnostic latency

A newly identified Parkinson’s disease symptom is always encouraging. A delayed diagnosis delays different types of treatment that could have improved a patient’s quality of life.

It takes an estimated 10 years from the appearance of the first incipient symptoms until a neurologist certifies the pathology. This decade is the diagnostic latency and it’s very difficult to reduce it.

Why? Because the initial symptoms are mild, they are confused with banal issues and the person tends not to consult health professionals.

Did you lose weight in an unexplained way? Do you have frequent tremors that prevent you from performing some daily activities? Do you have “mental gaps” that prevent you from remembering? It’s time to consult a professional.

New scientific discoveries are there to improve the quality of life. And diagnosing a disease in time is part of this process.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Bril, Andrea, et al. “A multifactorial study on nutritional status, binge eating and physical activity as main factors directly influencing body weight in Parkinson’s disease.” npj Parkinson’s Disease 3.1 (2017): 1-5.
  • Enrique, Parra Medina Luis, et al. “Latencia diagnóstica en la enfermedad de Parkinson y su relación con los síntomas prodrómicos motores y no motores.” eNeurobiología 10.25 (2019): 1.
  • Kim, Ryul, et al. “Association of Early Weight Change With Cognitive Decline in Patients With Parkinson Disease.” Neurology (2022).
  • Wills, Anne-Marie A., et al. “Association between change in body mass index, unified Parkinson’s disease rating scale scores, and survival among persons with Parkinson disease: secondary analysis of longitudinal data from NINDS exploratory trials in Parkinson disease long-term study 1.” JAMA neurology 73.3 (2016): 321-328.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.