People with type 2 diabetes being treated with thiazolidinedione compounds, such as Actos (pioglitazone) and Avandia (rosiglitazone), may be at lower risk of Parkinson’s disease, a pilot study suggests.
However, more work is needed to confirm a potential to prevent Parkinson’s in an at-risk patient population.
The study, “Decreased risk of Parkinson’s disease in diabetic patients with thiazolidinediones therapy: An exploratory meta-analysis,” was published in the journal PLOS ONE.
Thiazolidinediones — also called TZDs and glitazones — are a class of chemical compounds that enhance the activity of a specific receptor, called peroxisome proliferator-activated receptor-gamma (PPAR-γ). This promotes the deposition of fat into tissues within the body, reducing fat concentrations in the blood and improving insulin sensitivity in people with type 2 diabetes.
Evidence from studies in animal models of Parkinson’s disease suggest that TZDs also hold anti-inflammatory and neuroprotective activities. Several other studies have also shown that having type 2 diabetes increases by nearly a third the risk of developing Parkinson’s disease.
A randomized and controlled clinical trial (NCT01280123) was conducted in patients with early Parkinson’s but not diabetes, and its results indicated that treatment with Actos was not likely to prevent Parkinson’s progression. So far, observational and retrospective studies have also failed to confirm the neuroprotective effect of TZDs. As such, its use to treat Parkinson’s disease in diabetics remains controversial.
A team of researchers in China reviewed clinical data available from five published studies, covering a total of 347,556 patients with type 2 diabetes. Three of these five studies took place in Norway, the U.S. and the U.K.; the other two were done in Taiwan.
Three studies showed that treatment with TZDs was associated with lower incidence of Parkinson’s, whereas the other two studies — including one in the U.S. — did not find such a link. Still, a new analysis of pooled data from all five studies found a 30% reduced risk of Parkinson’s among diabetic patients being treated with TZDs compared to those who were not.
“This exploratory meta-analysis supports the value of using TZDs in reducing Parkinson’s disease incidence in diabetic patients,” the researchers wrote.
Additional studies are needed to further explore the impact of different TZDs on Parkinson’s progression, as well as to better define treatment regimens that could represent the most benefit, they added.
“Further prospective observational studies with larger sample size and more strict inclusion criteria including controlling for diabetes complication severity index, hypoglycemic drugs combination, sex ratio, and comorbidity [the presence of more than one disorder in the same person] are needed to guide whether randomized clinical trials are warranted,” the team suggested.