Smoking a joint could improve the memory of people with dementia, new research suggested
The chemical that makes people feel ‘high’ destroys rogue brain proteins behind the devastating illness .
Mice with a rodent form of Alzheimer’s disease also found their memory returned after being injected with THC (tetrahydrocannabinol).
Neuroscientist Dr Yvonne Bouter, of University Centre Goettingen, Germany, said: “Cannabis could be beneficial for Alzheimer’s disease.
“Treating Alzheimer’s disease mice with the psychoactive compound found in marijuana improves memory and reduces neuronal loss – suggesting a possible therapy for the human disease.”
But she warned the elderly should not begin smoking pot to ward off the neurological condition.
Explained Dr Bouter: “We did the same experiment in healthy mice – and they had problems learning.”
Her team injected the lab rodents with a synthetic form of THC for six weeks after they had been genetically engineered to develop Alzheimer’s like symptoms.
After six weeks of therapy they performed as well as healthy peers on a simple test – remembering where a shallow area of a small pool was located.
Sticky plaques of amyloid beta in their grey matter had been slashed by a fifth, said the researchers.
This is a protein that gathers into clumps during Alzheimer’s – killing neurons and triggering memory loss and confusion.
Meanwhile, a third group of mice that had dementia and were given a dummy treatment, or placebo, instead of the marijuana compound struggled on the task.
Dr Bouter, who presented her findings at a Society for Neuroscience meeting in San Diego, said: “The treated mice also lost fewer brain cells and their brains contained 20 per cent less of the sticky plaques associated with Alzheimer’s.”
The promising results add to growing evidence that cannabis may lead to the development of drugs that target the cause of dementia, rather than the symptoms.
Neuroscientist Professor Michael Taffe, of the Scripps Research Institute, La Jolla, California, who was no involved in the study, said: “Should you give Grandpa THC?
“You should probably be cautious.
“You could have something that is detrimental, if this does not translate to humans, or the person did not have the disorder.”
It has been suggested THC reduces inflammation, which only starts occurring in the brain once people are beyond the age of 30.
Previous research has shown it can remove amyloid beta from the brain.
This would explain why it has been shown to damage memory and thinking skills in younger individuals.
They do not have brain inflammation, so among this group the harm of THC would outweigh the benefits.
Joel Loiacono, of the US Alzheimer’s Association, said: “From our perspective, there are chemicals in marijuana that can be helpful, but we are not coming out in favour of marijuana use.
“They’re just beginning to do studies about cannabinoids. We are not closing off any avenues, the jury is just still out as we need to do more research in the area.”
Cannabis is now legal for medical and recreational use in several states across the country.
In a small study done on 10 Alzheimer’s sufferers, the drug was found to generally improve quality of life by improving sleep, reducing agitation and helping them eat more.
Dementia, which mainly affects older people, causes a deterioration in memory, thinking and behaviour and can impede someone’s ability to perform everyday activities.
It affects around 47.5 million people worldwide, according to the World Health Organisation, and it recently overtook heart disease to become the leading cause of death in England and Wales.
The most common type is Alzheimer’s disease.
Support of medicinal cannabis has skyrocketed in recent years, thanks to increasing evidence showing its therapeutic value for health conditions ranging from cancer to multiple sclerosis, arthritis and epilepsy.
By Mark Waghorn