Cannabis Could Treat Dementia, Cognitive Decline

Low-dose THC reversed brain aging in mice.

The aging process takes a toll on cognition and can result in decreased memory performance over time. Older individuals may have difficulties learning new tasks or multitasking. For patients with dementia, memory loss and cognition decline far exceed the norm.

A new study published by Nature Medicine suggests that cannabis may be able to reverse cognitive decline. The authors found that low-dose cannabis treatment reverted the brains of older mice to the state of 2-month-old animals, which could present new treatments for dementia.

Mice have a short life expectancy and can experience cognitive deficits as young as age 1, which makes them a good candidate for the study of cognition.

In the study, the authors administered a small amount of THC — the active ingredient in cannabis — to mice aged 2 months, 12 months, and 18 months over 4 weeks.

The mice were then assessed on learning capability and memory performance. Mice that were given the placebo were observed to have learning and memory losses associated with their age, according to the study. Older mice treated with cannabis were found to have the cognitive function of a younger animal.

"The treatment completely reversed the loss of performance in the old animals," said researcher Andreas Zimmer, PhD.

In previous studies, the authors found that the brain ages faster in mice without functional receptors for THC, called cannabinoid 1 (CB1) receptors. These receptors are proteins where THC binds and creates the intoxicating effects of the drug. THC imitates cannabinoids that are produced naturally and fulfill important functions in the brain, according to the study.

"With increasing age, the quantity of the cannabinoids naturally formed in the brain reduces," Dr Zimmer said. "When the activity of the cannabinoid system declines, we find rapid ageing in the brain."

To determine what effect THC treatment have on the brains of older mice, the authors examined brain tissue and gene activity.

They discovered that the molecular structure of the brain did not correspond with that of an older animal, but it resembled a younger animal, according to the study. The authors also found that the amount of links between nerve cells in the brain increased after treatment with THC, which suggests an increasing learning ability.

"It looked as though the THC treatment turned back the molecular clock," Dr Zimmer said.

The investigators administered a low dose of THC to prevent the mice from experiencing any psychoactive effects. In the future, the authors may explore the treatment in human patients to determine if low-dose THC can reverse aging and improve cognition in older adults, the study concluded.

"The promotion of knowledge-led research is indispensable, as it is the breeding ground for all matters relating to application. Although there is a long path from mice to humans, I feel extremely positive about the prospect that THC could be used to treat dementia, for instance,” said Svenja Schulze, the North Rhine-Westphalia science minister.