By Shana SagerThe Daily Northwestern
Researchers at Northwestern have discovered that men with primary progressive aphasia, a neurological disease, have a higher rate of vasectomy than men of the same age without dementia.
PPA patients lose the ability to express themselves because they can’t recall or understand words. Unlike Alzheimer’s disease, the disorder impairs language, not memory.
Sandra Weintraub, professor of psychiatry and behavioral sciences at NU’s Feinberg School of Medicine, said she thought a link between PPA and vasectomy was possible when one of her male patients suggested the correlation.
“I had a patient who was 47 years old who said that he was really thinking that his symptoms started not long after he had a vasectomy,” Weintraub said. “I couldn’t think about what a vasectomy would have to do with your brain.”
At a biannual PPA support group in Chicago, the same patient asked the other men present how many had the disorder. He then asked how many had had vasectomies. In the group, nine men had PPA and eight had had the surgery.
“I still couldn’t figure out why that would be important,” Weintraub said.
But she and a group of researchers from the Cognitive Neurology and Alzheimer’s Disease Center looked into it. They surveyed 47 men with PPA, 20 with Alzheimer’s, 30 with behavioral frontotemporal dementia and 57 who had no form of dementia.
Sixteen percent of the non-impaired men had vasectomies, whereas 40 percent of the men with PPA had the procedure.
Researchers also found that men who had the surgery saw an earlier onset of the disorder. Men who had vasectomies developed PPA at about 58 years of age, while men who hadn’t had the procedure didn’t get the disorder until nearly age 62.
Weintraub said the correlation could exist because the vasectomy procedure cuts the blood-testis barrier, the protective area between the blood and the testes.
The blood-testis barrier regulates the testes environment, Feinberg neurologist Chris Fahey said.
“The testes are fairly sequestered from the rest of the body,” Fahey said. “You don’t want toxins and things getting easy access to sperm and their maturation process. One of the consequences of this is that certain antigens aren’t exposed to the immune system.”
When this occurs, the body recognizes those antigens as foreign and forms anti-sperm antibodies. Anti-sperm antibodies are produced in 60 to 70 percent of men following a vasectomy.
“If you had a number of other types of conditions that involved different organs like the liver, like the pancreas, the body already knows that those antigens exist,” Fahey said. “It won’t attack those antigens because it knows they’re cells.”
The next step for the research is to explore the correlation more specifically, said Nancy Johnson, assistant professor of psychiatry at Feinberg.
“Do the patients that had vasectomies form these anti-sperm antibodies?” Johnson said. “And can it cause problems at the brain cell level?”
Many questions remain unanswered. Researchers now will investigate why similar correlations don’t exist between vasectomies and other forms of dementia, such as Alzheimer’s.
“We are at the very beginning of a long process,” Johnson said.
Reach Shana Sager at [email protected].
