14 DAY TRIAL // Vasectomy is a permanent male birth control surgery in which vasa deferentia, tubes that connect testes to the urethra and through which sperm moves, are cut.
But a recent study at Northwestern University has revealed a link between an unusual form of dementia and vasectomy.
This condition, named Primary Progressive Aphasia (PPA), is a neurological disease in which people have trouble recalling and understanding words, losing the ability to express themselves and understand speech, something very different from Alzheimer's disease, the most common form of dementia, in which a person loses memory, while Alzheimer's patients lose interest in their hobbies, family life and can turn into "vegetables".
Oddly, PPA patients are still able to maintain their hobbies and perform other complicated tasks for a number of years before the severing of the disease: they keep gardening, building cabinets and even navigating a city subway system.
Sandra Weintraub, principal investigator and professor of psychiatry and behavioral sciences and director of neurology at Northwestern's Feinberg School of Medicine, noticed this link as when a patient, 43, experienced speech problems after his vasectomy.
Weintraub's team surveyed 47 men with PPA treated at Northwestern's Cognitive Neurology and Alzheimer's Disease Center and 57 volunteers with no cognitive impairment, aged 55 to 80.
Of the healthy men, 16 % had undergone a vasectomy, while 40 % of the PPA patients had had the surgery.
"That's a huge difference. It doesn't mean having a vasectomy will give you this disease, but it may be a risk factor to increase your chance of getting it," said Weintraub.
Moreover, those who suffered a vasectomy developed PPA at a younger age (58 years) than PPA patients who did not (62 years.)
Previous research linked frontotemporal dementia (FTD), another type of dementia (linked to personality changes, lack of judgment and bizarre behavior, turning in compulsive gamblers or sexually demanders) to vasectomy.
The study did not find any link between vasectomy and Alzheimer's.
FTD and PPA patients developed a common brain condition, completely different from Alzheimer's, which explains their different symptoms.
In FTD, the frontal lobes, responsible with the personality and active decisions, are damaged; in PPA, the language centers are the first targeted.
The researchers believe that vasectomy destroys the protective blood-testis barrier, which prevents blood-borne infections and toxic compounds from entering the semen.
After a vasectomy, the semen enters into the blood, and the immune system perceives the sperm as invading foreign germs, increasing anti-sperm antibodies in 60 to 70 % of the males.
"These antibodies might cross the blood-brain-barrier and cause damage resulting in dementia. There are other neurological models of disease which you can use as a parallel," Weintraub said.
"Certain malignant tumors produce antibodies that reach the brain and cause an illness similar to encephalitis", she noted.
The researchers said that more investigations in larger number of subjects should be carried out.