Adding marijuana to the treatment of Alzheimer’s Disease “is safe and a promising treatment option”, Israeli researchers conclude, in the latest study on the burgeoning practice.

Alzheimer’s Disease is a devastating and fatal degenerative neurological disease affecting more than five million Americans today. One in three seniors will die with Alzheimer’s or another dementia, and Alzheimer’s is the sixth leading cause of death in the nation, costing America about $203 billion in 2013.

Past studies indicate the active ingredients in cannabis can provide palliative relief to Alzheimer’s patients with dementia — calming them down and allowing them to sleep. Cell studies also indicate cannabis’ active ingredients could prevent the onset and progression of Alzheimer’s, by interrupting the cycle of beta-amyloid plaque creation thought to cause Alzheimer’s Disease.

Researchers at the Abarbanel Mental Health Center and the Sackler Faculty of Medicine at Tel-Aviv University, in Israel, along with the Department of Psychology, at Bar-Ilan University conducted one of the first clinical studies of cannabis on human Alzheimer’s patients.

The main active ingredient in cannabis “tetrahydrocannabinol (THC) is a potential treatment for Alzheimer’s disease (AD)” researchers wrote. They wanted to measure the safety and efficacy of giving a medical cannabis oil containing THC as an add-on to existing Alzheimer’s drugs. Their goal: relieving the terrifying behavioral and psychological symptoms of dementia.

Eleven patients were recruited into an open-label, month-long trial. Ten patients finished the trial, and researchers reported “significant reduction” in mental illness severity, especially with regard to delusions, agitation/aggression, irritability, apathy, sleep, and caregiver distress.

“Adding [medical cannabis oil] to [Alzheimer’s Disease] patients’ pharmacotherapy is safe and a promising treatment option,” researchers concluded.

Read: “Safety and Efficacy of Medical Cannabis Oil for Behavioral and Psychological Symptoms of Dementia: An-Open Label, Add-On, Pilot Study”

Smell the Truth editor David Downs is the author of The Medical Marijuana Guidebook, out in paperback this February (Whitman Publishing).