New York : The incidence of different types of Parkinsonism, including the most common type, Parkinson’s disease, has increased significantly in the US in 30 years from 1976 to 2005, a new study says.

The risk of developing Parkinsonism has particularly gone up for men of over 70 years of age, the findings showed.

According to the researchers, this is the first study to suggest such an increasing trend.

The study showed that men of all ages had a 17 per cent higher risk of developing Parkinsonism and 24 per cent higher risk of developing Parkinson’s disease for every 10 calendar years.

The study also showed that men aged 70 and older had an even greater increase — a 24 percent higher risk of developing Parkinsonism and 35 per cent higher risk of developing Parkinson’s disease for every 10 calendar years.

Using the Rochester Epidemiology Project, the Mayo Clinic researchers were able to look at the complete medical records — from birth to death — of anyone in Olmsted County, Minnesota, who received at least one of the diagnoses related to Parkinsonism.

The records were reviewed by a movement disorders specialist to confirm the diagnosis and to classify different types of Parkinsonism.

“We have reasons to believe that this is a real trend,” says Rodolfo Savica, lead author and neurologist at Mayo Clinic in Minnesota.

“The trend is probably not caused merely by changes in people’s awareness or changes in medical practice over time. We have evidence to suggest that there has been a genuine increase in the risk of Parkinson’s disease,” Savica noted.

The researchers point to environmental and lifestyle changes as potential causes for the increase.

“There has been a dramatic change in exposure to some risk factors in the United States,” Savica said.

“We know that environmental agents like pesticides or smoking or other agents in the environment have changed in the last 70 years or so. Changes in exposure to a number of risk factors may have caused Parkinson’s disease to rise,” Savica explained.

The findings appeared in the journal JAMA Neurology.

Parkinsonism is the umbrella term that includes Parkinson’s disease but also may include other disorders. The diagnosis of parkinsonism requires the presence of slowness of movement and at least one other symptom — a tremor while at rest, muscle rigidity or a tendency to fall.