02/02/2026 | Ravenna Alves | Repórter MT

https://www.reportermt.com/saude/estudo-mostra-eficacia-da-cannabis-no-tratamento-do-alzheimer/231682 

Clinical trial with elderly patients evaluated medicinal extract of the plant and observed cognitive gains over six months.

A study conducted by researchers at the Federal University of Latin American Integration (Unila), in Paraná, observed improved memory in Alzheimer's patients after the use of medicinal cannabis.

The research, published in the Journal of Alzheimer’s Disease in October 2025, followed a group of elderly patients for six months and identified improvements in memory tests among those who received the plant extract.

The trial was conducted with 28 volunteers aged 60 to 80 and is described by the authors as the longest ever done in the world with cannabinoids in people diagnosed with the disease.

The researchers evaluated the effects of a full-spectrum extract, which combines small doses of THC (tetrahydrocannabinol) and CBD (cannabidiol), two compounds present in cannabis.

According to the coordinator of the work, Francisney do Nascimento, the study followed the model considered most rigorous for clinical research.

“In this type of research, half of the group receives the medication and the other half receives the placebo, and at the end the results are compared,” he details in a statement.

Results in cognitive tests
At the end of the 26 weeks, the participants who used the extract showed cognitive improvement measured by a widely used instrument in the evaluation of mental functions, the Mini-Mental State Examination (MMSE).

For Nascimento, the finding is noteworthy because the benefit appeared precisely in tests related to memory, and not only in behavioral symptoms.

“This is the world’s first clinical trial showing that cannabis improves memory in Alzheimer’s patients. Other studies show that it reduces agitation and anxiety. But the memory test, in fact, the first article was ours,” says the researcher.

Today, Alzheimer’s is one of the leading neurodegenerative diseases and has a direct impact on the quality of life of patients and caregivers. Available treatments are still limited and offer modest gains, which increases interest in new therapeutic approaches.

Why might cannabis act on the brain?

Researchers explain that cannabinoids have been studied for their action in processes associated with disease progression.

The hypothesis is that these substances may reduce inflammation in brain tissue and oxidative stress, two factors that contribute to the degeneration of neurons.

“Studies conducted with rats in laboratories have already demonstrated that THC can promote neurogenesis in the hippocampus, the region of the brain responsible for memory,” explains Nascimento.

Safety and Next Steps
Another point highlighted in the study was the absence of relevant adverse events during follow-up, suggesting that the use of the extract, at the doses evaluated, was well tolerated by the participants.

For the physician responsible for the trial and professor of the medicine course at Unila, Elton Gomes da Silva, the results broaden the interest in new research with different combinations and concentrations of the compounds.

According to him, other studies are already underway at the university to compare dosages and explore broader effects in patients with Alzheimer's.