As populations age across the globe, Alzheimer’s disease continues to place growing pressure on families, healthcare systems and aged care services. Despite decades of research, available treatments remain limited, offering modest symptom relief rather than slowing the underlying disease process. A new clinical study from Brazil, however, is drawing international attention for exploring an unconventional approach: microdosing cannabis without producing psychoactive effects.
Published in the Journal of Alzheimer’s Disease, the small but carefully designed trial investigated whether extremely low doses of cannabis extract could stabilise cognitive decline in people with mild Alzheimer’s disease. While the findings are preliminary, researchers say they represent an important step towards a new way of thinking about cannabinoids and brain ageing.
Microdosing refers to the administration of doses so small they sit well below the threshold that produces noticeable psychological effects. In this study, participants received a daily oil containing just 0.3 milligrams each of THC and CBD, the two most widely studied cannabinoids. At these levels, patients did not experience the intoxication commonly associated with cannabis use.
The trial involved 24 people aged between 60 and 80 who had been diagnosed with mild Alzheimer’s disease. Participants were randomly assigned to receive either the cannabis extract or a placebo for 24 weeks, with neither the patients nor researchers knowing who received which treatment until the study concluded.
Cognitive performance was assessed using established clinical tools, including the Mini Mental State Examination, a widely used measure of memory, orientation and attention in people with dementia. At the end of the trial, participants receiving the cannabis extract showed stabilisation in their cognitive scores. By contrast, those in the placebo group demonstrated the gradual decline typically expected in Alzheimer’s disease.
The difference between groups was modest but clinically meaningful, with cannabis recipients scoring around two to three points higher on average. While this does not represent a reversal of the disease, researchers argue that even slowing decline may significantly affect quality of life and functional independence.
Importantly, the microdosing approach did not improve non cognitive symptoms such as mood or overall wellbeing. However, the study also reported no increase in adverse effects, reinforcing the safety profile of ultra low dose cannabinoids in older adults.
Interest in cannabinoids for neurodegenerative disease is not new. The brain’s endocannabinoid system plays a key role in regulating inflammation, synaptic plasticity and neural protection. Previous animal studies have shown that endocannabinoid activity declines with age, potentially leaving the brain more vulnerable to inflammation and cognitive deterioration.
In landmark mouse studies, very low doses of THC were found to restore learning ability and synaptic density in older animals, effectively shifting brain activity patterns closer to those seen in younger mice. These findings laid the groundwork for exploring microdosing in humans, where higher doses may be poorly tolerated or culturally stigmatised.
Laboratory research also suggests cannabinoids may reduce neuroinflammation, a recognised contributor to Alzheimer’s pathology. Chronic inflammation in the brain is associated with accelerated neuronal damage, and modulating this process without altering consciousness could offer a valuable therapeutic pathway.
One of the biggest obstacles to cannabis based therapies remains public perception. Many patients and clinicians associate cannabis with intoxication, dependence or legal concerns. The microdosing approach directly challenges these assumptions by demonstrating that biological effects can occur at doses too low to produce a high.
This may be particularly relevant for older people, who are often sensitive to medication side effects and already managing complex drug regimens. A treatment that offers potential cognitive benefit without sedation or behavioural changes could be more readily accepted in aged care and community settings.
While the study represents a global first, researchers are cautious about overstating its implications. The sample size was small, the follow up period relatively short, and benefits were confined to specific cognitive measures. Larger trials will be needed to determine whether microdosing cannabis can genuinely slow disease progression rather than temporarily stabilising symptoms.
Future research is expected to incorporate brain imaging, inflammatory markers and longer observation periods to better understand how cannabinoids interact with Alzheimer’s pathology. Questions also remain around optimal dosing, treatment duration and whether benefits extend to people with more advanced disease or mild cognitive impairment.
For now, the findings offer a glimpse of a possible new therapeutic avenue at a time when innovation in dementia care is urgently needed. While cannabis is far from a cure, microdosing may represent a subtle but meaningful shift in how neurodegenerative disease is approached, focusing less on dramatic interventions and more on gentle biological support for the ageing brain.
