Up to 1.5% of people in their late 60s and as many as 1 in 13 over age 86 suffer from idiopathic normal pressure hydrocephalus (iNPH). The condition is caused by a buildup of cerebrospinal fluid in the brain that leads to walking and balance problems, memory decline and bladder control issues.

Now a new international study led by Johns Hopkins Medicine researchers offers definitive evidence that shunt surgery can restore mobility and physical safety in older adults with iNPH. Published in the New England Journal of Medicine, the project is the first large, double-blind, placebo-controlled study to resolve decades of debate on whether shunts truly help patients.

“Although shunts have been used for 50 years, skepticism persisted because of the placebo effect and the risks of operating in frail, elderly patients,” says Mark Luciano, principal investigator and director of the Johns Hopkins Hydrocephalus and Cerebral Fluid Center. “This study shows surgery is both effective and has an acceptable safety profile. We’ve proven this treatment works, definitively and safely, in the most rigorous type of study possible.”

Conducted by the Johns Hopkins Cerebral Fluid Center in the Department of Neurosurgery, the study enrolled 99 patients across 17 centers in the U.S., Canada and Sweden. All patients underwent shunt surgery and received a functioning shunt. However, in half, the shunt was initially adjusted to a placebo setting.

After three months, patients with functioning shunts walked significantly faster than they had before surgery, while the placebo group showed virtually no change. On average, walking speed in the shunt group improved by 0.23 meters per second — more than double the threshold considered by researchers to be a meaningful change in older adults. Some 80% of patients with a functioning shunt achieved meaningful improvement, compared with just 24% of those in the placebo group.

Patients in the treatment group also displayed improved balance and reported fewer falls.

Despite its potential for treatment, iNPH is often overlooked. Researchers report that only about 20% of patients who could benefit from surgery are referred for evaluation because their symptoms are dismissed as normal signs of aging.

Yet diagnosis can be simple. “If there appears to be imbalance that’s increasing, or memory loss that’s increasing, it’s a diagnosis that can be explored with a routine brain scan,” says Luciano. “If the ventricles are enlarged and the symptoms are there, then patients can be referred to specialists who can further evaluate and treat.”