By analyzing more than 100 million drug prescriptions in Norway, researchers found that patients who used glitazones (GTZs) saw their risk of Parkinsonâ€™s disease reduced by more than a quarter.
GTZs â€“ also known as thiazolidinediones â€“ are approved in the United States for the treatment of type 2 diabetes. They work by increasing the bodyâ€™s sensitivity to insulin, which is the hormone that regulates blood sugar levels.
â€œBased on current evidence, it remains unclear whether GTZs have a neuroprotective effect in PD [Parkinsonâ€™s disease],â€ note Tzoulis and colleagues.
GTZs reduced Parkinsonâ€™s risk
Aiming to gain a better understanding of the link between GTZ use and Parkinsonâ€™s risk, the researchers analyzed data from the Norwegian Prescription Database, which holds data on all medications dispensed in pharmacies across Norway, as well as information on the patients to whom these medications are prescribed.
The researchers looked at the link between the use of GTZs, metformin â€“ which is the primary drug prescribed for type 2 diabetes â€“ and the development of Parkinsonâ€™s disease.
The study revealed that, compared with users of metformin, patients who used GTZs were 28 percent less likely to develop Parkinsonâ€™s disease.
They are unable to explain the precise mechanisms behind their findings, but they speculate that GTZs might improve the function of mitochondria. These are organelles that produce energy for cells, enabling them to function.
In a previous study, Tzoulis and team found that patients with Parkinsonâ€™s disease experience a reduction in mitochondrial production. â€œIt is possible,â€ they say, â€œthat GTZ drugs ameliorate these defects by increasing mtDNA [mitochondrial DNA] synthesis and overall mitochondrial mass.â€
Still, the team says that further studies are needed to investigate this possible mechanism. â€œIf we understand the mechanisms behind the protection, then we have a chance to develop a new treatment,â€ says Tzoulis.
A â€˜step toward solving the Parkinsonâ€™s riddleâ€™
The researchers cite a number of limitations to their study. For instance, the team did not have data on the GTZ or metformin dose each patient was using, so they are unable to determine the dose-response relationship between diabetes medication and the risk of Parkinsonâ€™s disease.
Also, the researchers note the lack of information on the diabetes stage of each patient. â€œHowever,â€ they say, â€œas diabetes has not been shown to have a definite effect on the risk for PD, we find it unlikely that treatment stage would significantly bias our results.â€
Because the study only included patients who had been diagnosed with diabetes, the findings cannot be generalized to the population as a whole.
That said, the team believes that the study could lead to new prevention and treatment strategies for Parkinsonâ€™s disease, a condition that is diagnosed in around 60,000 people in the U.S. every year.
â€œWe have made an important discovery, which takes us a step further toward solving the Parkinsonâ€™s riddle.â€
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