A cannabis-based drug could help people with Alzheimer's disease by giving them the "munchies", researchers say.
The drug is an artificial version of a cannabis component
Patients with the condition often experience weight loss because they stop recognising when they are hungry.
The study does not suggest they should be given cannabis to smoke - instead, they tested a synthetic version of a cannabis extract.
It was found the cannabinoid led to weight and reduced agitation, another symptom of the disease.
The researchers from the Meridian Institute for Aging in New Jersey looked at a drug called dronabinol which is an artificial version of delta-9 THC, the active ingredient in cannabis.
The drug has already been approved in the US for the treatment of anorexia in patients with HIV/Aids and nausea associated with chemotherapy.
In the UK, a THC cannabinoid is also being tested in a trial to see if cannabis-based drugs can ease post-operative pain.
In the latest US trial, 48 patients with an average age of 77 who had experienced problems with agitation and had been diagnosed with anorexia were studied.
All lived in a dementia unit or a care home.
Researchers assessed their cognitive skills and looked at how they coped with daily life.
They were then given daily doses of five milligrams of dronabinol per day, which was gradually increased to 10 mg a day.
They were also given anti-psychotic drugs, which reduce delusions and have a calming effect, and at least four other medications to control behaviour.
After a month, it was found all the patients had gained weight.
Two thirds experienced a significant improvement in agitation.
No adverse events such as falls, seizures or depressions were reported.
'Upsetting and stressful'
Dr Joshua Shua-Haim, medical director at the Meridian
Institute for Aging, who led the study, said: "Our research suggests dronabinol may
reduce agitation and improve appetite in patients with Alzheimer's disease, when
traditional therapies are not successful.
"It's important to look at all the aspects of Alzheimer's disease that
contribute to quality of life for patients, family members and caregivers.
"Agitation and weight loss are upsetting and stressful as the patient's needs
become ever more demanding."
The research was presented to the annual conference of the International Psychogeriatric Association in Chicago.