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Cannabis Extract Calms Brain Inflammation in Aged Rats

A ∆9-THCA-enriched cannabis extract reduced hippocampal inflammation markers in aged rats but also lowered their treadmill endurance.

By Dr. Josh Axe · November 12, 2026 · 1 source · Watch

Photo: Pexels

At a glance

What they found: 94-98% fewer Iba-1-positive microglial cells in the hippocampus across all doses.
Who was studied: Aged Sprague-Dawley rats, a standard rodent model used in aging research.
What it doesn't show: Whether it works the same way in people.

A cannabis-derived extract high in ∆9-THCA reduced markers of brain inflammation by as much as 97.9% in aged rats, according to a study published in November 2026 in Pharmaceuticals.

93.5-97.9%less microglia marker

6-weekrat study

0.5-2.0mg/kg doses

Aged Sprague-Dawley rats received an oral, full-spectrum cannabis extract enriched in ∆9-THCA at 0.5, 1.0 or 2.0 mg/kg, given five days on and two days off for six weeks. Researchers tracked body weight, treadmill endurance, balance-beam coordination, blood chemistry, organ tissue and brain markers of inflammation and cell death after the animals were euthanized.

Across all three doses, hippocampal tissue showed 93.5 to 97.9% fewer cells marked by Iba-1, a protein that flags activated microglia, the brain's resident immune cells, with the most variability at the lowest dose. The extract also reduced age-related weight loss, most preserved at the highest dose, 2.0 mg/kg, and reduced markers of apoptotic signaling, a process tied to programmed cell death. Liver and kidney blood markers stayed within normal ranges at every dose.

The authors say this reflects a phenotypic shift toward metabolic and neuroinflammatory stability. Microglia are the brain's cleanup and alarm cells; chronically overactive microglia are tied to the low-grade inflammation researchers call inflammaging. The tradeoff was a dose-dependent fall in peak treadmill endurance, which the authors attribute to the rats refusing to continue the task rather than any loss of neuromotor coordination.

Brain Inflammation Marker Reduced 93.5-97.9% With Extract

Pharmaceuticals, 2026, Tudorancea et al.

This is a rat study, not a human trial, so whether the same brain-calming effect or endurance tradeoff would appear in people is untested. Dosing was intermittent rather than daily, and the endurance drop was behavioral rather than a measured physical limit.

Dr. Axe’s Take

A cannabis extract high in THCA calmed brain inflammation in old rats while making them less willing to push through a treadmill test, and that tradeoff deserves attention rather than a quick dismissal. Inflammaging, the low-grade inflammation that builds with age, responds to things we already know calm an overactive microglial response: omega-3-rich fish, turmeric, regular walking or strength training, and good sleep, since that's when the brain clears inflammatory debris. I would not take this as a reason to start any cannabis product on your own.

— Dr. Axe

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Study summary

Who: Aged Sprague-Dawley rats, a standard rodent model used in aging research
Design: Controlled animal study, six weeks, intermittent oral dosing (5 days on, 2 days off)
Dose: 0.5, 1.0, or 2.0 mg/kg of a ∆9-THCA-enriched cannabis extract
Primary result: 93.5-97.9% fewer Iba-1-positive microglial cells (brain inflammation marker) in the hippocampus across all doses
Secondary: Reduced age-related weight loss, most preserved at 2.0 mg/kg; reduced apoptotic (cell-death) signaling; dose-dependent drop in peak treadmill endurance from task refusal, not impaired coordination
Funding / conflicts: Funder listed in the journal record: "Grigore T. Popa" Universty of Medicine and Pharmacy. Conflicts not reported in the abstract.
Date: Nov 7, 2026