UF scientists to test testosterone on Parkinson's symptoms in men

April 8, 2003

GAINESVILLE, Fla. — University of Florida researchers will study whether giving testosterone to men with Parkinson’s disease who have low levels of the hormone will curb some symptoms of the disease.

Boosted by a $250,000 grant from the Michael J. Fox Foundation for Parkinson’s Research, Dr. Michael S. Okun said scientists at UF’s Evelyn F. and William L. McKnight Brain Institute will begin this week to determine whether testosterone will help men with Parkinson’s disease.

“I noticed many Parkinson’s disease patients who had the ‘dwindles’ – low energy, fatigue, loss of quality of life – but it didn’t seem related to their movement symptoms,” said Okun, an assistant professor of neurology in the UF College of Medicine. “That led us to look for reasons for these symptoms.”

In a preliminary study, Okun reported improvements in the symptoms of men with Parkinson’s disease who applied a testosterone gel to their skin, but the researchers did not compare the patients with a similar group given an inactive version of the gel.

Now, the research will include a control group of patients to determine whether the positive results could have stemmed from the so-called placebo effect, in which patients show improvements even with inactive drugs or therapies, Okun said. In addition, instead of receiving testosterone via a topical gel, participants will be given daily injections of 200 milligrams of the hormone. Thirty patients will take part in the clinical trial on an outpatient basis for eight weeks.

The UF research regarding testosterone may hold implications for women as well as men. Okun said women with Parkinson’s disease who have had their ovaries removed may display the same nonmovement-related symptoms as men with low levels of testosterone.

More than 4 million people are affected by Parkinson’s disease worldwide, including more than 500,000 Americans. The disease causes tremors, rigidity, impaired balance and emotional changes, and usually affects people over 50, according to the National Institute of Neurological Disorders and Stroke.

There is no cure, but a variety of medications may provide relief from the symptoms, and surgery may be an option when response to medications is unsatisfactory.

Parkinson’s disease occurs when nerve cells in an area of the brain known as the substantia nigra become impaired or die. Normally, these nerve cells produce dopamine, a chemical messenger responsible for transmitting signals that enable smooth, purposeful muscle activity.

Initial findings Okun published in the November issue of the Archives of Neurology revealed patients who received testosterone lost an average of two nonmovement-related symptoms, which include fatigue, energy problems, sexual dysfunction and depression.

During the study, 10 men with Parkinson’s and low testosterone levels were given a testosterone gel to rub on their shoulders, chest and abdomen once daily. Four of the patients were followed for one month and six were followed for three months.

After one month and three months, researchers found testosterone levels had increased and patients showed an average of six symptoms related to testosterone deficiency, a drop from the previous average of eight. Patients reported no adverse effects.

“We believe there may be tremendous promise for patients who receive testosterone therapy,” said Okun, co-director of the Movement Disorder Center at UF’s McKnight Brain Institute. “The Michael J. Fox Foundation is very forward-thinking in regard to studies that need to be done, but which might not be receiving the sponsorship needed to get it done.”

The foundation selected Okun’s study for funding because it collected data directly from patients and strived to establish clear benefits for Parkinson’s disease patients by assessing existing therapies typically used in other contexts.

“Many of the projects we have chosen to fund are exciting not only because they will advance our understanding of the disease but also because they are positioned to quickly translate into clinical studies based on success of their final outcomes,” said William Langston, chief scientific adviser to the Fox foundation and chief executive officer of The Parkinson’s Institute.

Okun will be among seven speakers who will discuss the latest developments regarding Parkinson’s disease on Saturday, when UF’s Movement Disorder Center will present a daylong public program in recognition of World Parkinson’s Disease Day. Call (352) 392-3491 for information.