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Metabolic Syndrome & Increased Parkinson’s Disease Risk

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All Science News articles summarize a research study and are not an official opinion, endorsement or position of the Parkinson’s Foundation’s.

Metabolic Syndrome (MetS) is a group of conditions that occur together that result in insulin resistance and increase the risk of heart disease, stroke and diabetes. According to a new study, MetS may be associated with Parkinson’s disease (PD).

While MetS can be prevented, controlled, treated and even reversed. It is not always easy to treat, since it is a cluster of five interrelated risk factors:

  1. high blood pressure
  2. high blood sugar (fasting glucose)
  3. high levels of triglycerides (a type of fat in your blood)
  4. low levels of HDL (the “good” cholesterol)
  5. a large waist circumference (over 40 inches for men and over 35 inches for women)

MetS is associated with developing a number of diseases, including heart disease, stroke, and type-2 diabetes. It is also associated with an increased all-cause mortality risk (meaning, dying from any cause). Additionally, there’s mounting evidence suggesting that oxidative stress is a major component of MetS-associated diseases – and Parkinson’s disease also has been shown to have a strong oxidative stress component. Thus, there may be shared disease pathways that could be targeted for future treatments and interventions.

A recently published study in the journal, PLOS Medicine, titled, "Metabolic syndrome and risk of Parkinson disease: A nationwide cohort study" (Nam et al., 2018), approached this important investigation in a big way. Spanning a 5-year period (2009 through 2012), the research scientists analyzed the health check-up data of nearly the entire South Korean population who met the study criteria, e.g., study individuals had to be 40 years of age or older and have no prior diagnosis of PD.

Ultimately, 8,215,180 men and 8,948,380 women (for a total of 17,163,560 people) were part of the study analyses. Demographics and lifestyle data were gathered through self-reporting questionnaires, including comorbidities (hypertension, diabetes mellitus, dyslipidemia, ischemic heart disease and stroke), as well as smoking status, alcohol consumption, income, age, gender, and of course, their specific test results for all 5 MetS risk factors. Of note, study participants were diagnosed as having MetS if they had 3 or more of the 5 risk factors. 

Results

  • At baseline, 5,848,508 of the individuals (34.1% of the total study population) were diagnosed as having MetS.
  • Upon follow-up, 44,205 individuals were diagnosed with PD.
  • The rate of PD incidence was 2.2 times higher in those with MetS compared to those who didn’t have MetS.
  • Overall, individuals who had MetS had a 24 percent higher risk of PD than those without MetS.
  • Having even just one of the 5 MetS risk factors increased an individual’s PD risk; and, that PD risk increased with each additional risk factor.
    • Individuals with 3 MetS risk factors were at 31% higher risk of PD, compared to those without any risk factors.
    • Individuals with all 5 MetS risk factors were at 66% higher risk, compared to those without any risk factors.
  • Individuals 65 years and older were all shown to be at increased risk for PD, with the greatest PD risk for those with MetS; this association was particularly prominent in women.
  • Even after adjusting for potential confounders (age, sex, smoking, alcohol consumption, physical activity, income, body mass index, kidney function, and history of stroke), individuals with MetS had an increased risk of PD compared to those without MetS. 

What Does This Mean?

This study suggests that not only does having MetS risk factors increase your risk for PD, but also, the more risk factors you have, the more likely you are to develop PD. That being said, the jury is still out as to what actually causes MetS in the first place.

Many of the risk factors of metabolic syndrome are associated with insulin resistance (IR). More and more studies suggest that IR negatively impacts dopamine functioning in the brain. And PD symptoms – including tremors, stiffness, and slowness of movement – are caused by a lack of dopamine in the brain;  hence, why a drug that replenishes the brain's reduced supply of dopamine, i.e.,  levodopa, helps diminish those symptoms.

Perhaps the biggest take-away is three-fold:

  1. Improving our understanding of the relationship between the components of MetS and PD could help us better understand the pathophysiology that links the two.
  2. Adopting a healthier lifestyle (better food choices, more exercise and medications, if prescribed) is a well-documented path to halt, and even reverse MetS – which, according to this study, may also reduce your risk for developing PD.
  3. Being able to identify people at increased risk for developing PD is vital information to have, as mounting an early intervention strategy as described above could potentially make a big difference. 

Learn More

The Parkinson’s Foundation believes in empowering the Parkinson’s community through education. Learn more about this topic in the below Parkinson’s Foundation resources or by calling our free Helpline at 1-800-4PD-INFO (473-4636).

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