The study published in the Journal of Alzheimer’s Disease in December 2025[1] was conducted by scientists from the Federal University for Latin American Integration (UNILA). It involved 28 elderly patients with mild Alzheimer’s disease, who received daily doses of 0.350 mg THC and 0.245 mg CBD or placebo for 26 weeks. Cognitive functions were assessed using the Mini-Mental State Exam (MMSE). Patients receiving the cannabis extract maintained stable scores, while the placebo group experienced decline, with a difference of two to three points on the 30-point scale. Professor Francisney Pinto Nascimento, leading the research, designed the trial[2] as randomized, double-blind, and placebo-controlled. According to NORML’s deputy director, Paul Armentano, the cognitive improvement results directly[5]from the cannabinoid intervention, not from improved quality of life.
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Study Details and Results
Microdoses of the extract did not produce psychoactive effects nor differences in adverse events between groups. There was also no improvement in non-cognitive symptoms such as depression or quality of life, attributed to the very low doses. The study was based on earlier findings from 2017 by Andreas Zimmer and Andras Bilkei-Gorzo, who demonstrated that * low doses of THC restore cognitive functions in older mice[6] by reversing gene expression changes in the hippocampus. The endocannabinoid system, which regulates brain activity and provides neuroprotection[4]* weakens with age. Cannabinoids may protect cognitive functions by reducing brain inflammation.
Mechanisms of Cannabinoids’ Action
The cannabis extract came from ABRACE, Brazil’s largest patient association with nearly 50,000 members[9]*, which received no funding from cannabis industry companies. Although this is the longest clinical trial assessing cannabinoids in patients with Alzheimer’s, its limitations include the small sample size and evaluation of only one dimension of cognitive function. The researchers emphasize the need for larger trials with longer follow-up and the use of biomarkers such as neuroimaging to confirm whether cannabis can slow disease progression.