South African Review Explores Cannabis and Brain Health

Could cannabis provide starting materials for medicines that protect brain cells? Answering that question requires more than showing that an extract changes a laboratory measurement. Researchers need to establish what it contains, how it works, and whether its effects survive the journey from an experimental dish to a living brain.

A new systematic review, “Medicinal plants in South Africa with neuroprotective potential,” brings that challenge into focus.¹ Published in the South African Journal of Botany, it examines 29 preclinical studies, including three involving Cannabis sativa. The findings support continued investigation, while highlighting how much useful work lies between a promising plant extract and a dependable treatment.

The most interesting opportunity is to make cannabis research more specific: identify which preparations influence which biological processes, then test whether those effects preserve meaningful brain function.

Why Cannabis Attracts Neuroprotection Research

Neuroprotection means preserving the structure or function of nerve cells. Researchers studying neurodegenerative diseases investigate several connected problems, including disrupted energy production, inflammation, oxidative stress, and abnormal protein accumulation.

Oxidative stress occurs when reactive molecules overwhelm a cell’s protective systems. Think of a workshop generating more sparks than its safety equipment can contain. Reducing those sparks may help, but it does not automatically repair damaged machinery or restore the workshop’s output.

That distinction matters when reading cannabis studies. An extract that reduces a marker of oxidative stress has demonstrated a potentially useful biological effect. Showing that it preserves memory, movement, or independence requires additional evidence.

The review also examines cholinesterases, enzymes that break down the signaling molecule acetylcholine, and beta-secretase, an enzyme involved in the production of amyloid-beta. These are relevant research targets, but changing their activity in an assay does not establish that a preparation slows Alzheimer’s disease.

What the South African Review Examined

The researchers searched Google Scholar, Scopus, ScienceDirect, and Web of Science, with a stated search date of July 31, 2025. Their selection focused on plants available in South Africa that had been investigated experimentally for neurological applications.

The review classifies its 29 included studies as eight in vitro assays, 12 cell-based experiments, and nine animal-based studies. These categories describe the full collection, not the cannabis subset. No human treatment trials formed part of that evidence base.

South Africa provides the botanical and ethnomedicinal context. It does not mean every included plant is indigenous to the country or that every experiment was conducted there. The collection spans multiple plant families and preparations, making it a map of research possibilities rather than a ranking of proven treatments.

What the Cannabis Studies Reported

The three cannabis entries examined different plant materials and extraction approaches. One investigated leaf extracts in excised rat brain tissue, reporting increased glucose consumption alongside changes in oxidative stress and cholinergic dysfunction. Because the tissue was studied outside the animal, those findings do not demonstrate improved behavior or memory in a living subject.

A second study investigated preparations from leaves, flowers, fruits, and seeds and reported inhibition of cholinesterase and beta-secretase activity. A third examined flower extracts, including aqueous and hexane preparations, using enzyme tests and Neuro-2a cells, a laboratory cell line used in neuroscience research.

The table summarizes the review’s cannabis entries. Its findings and experimental settings come from the supplied paper.

These results identify several pathways worth following. They do not establish a single cannabis mechanism, an effective human dose, or a preferred consumer product.

Why the Extract Matters as Much as the Plant

“Cannabis extract” can sound like a standardized ingredient. Scientifically, it is closer to a description of where a mixture came from. Leaves and flowers can supply different chemical profiles, while the extraction solvent determines which constituents are collected.

The original flower-extract experiment, published in 2022 and included in the review, illustrates this distinction. Its water-based preparation showed activity against both tested enzymes, while the hexane preparation reached the reported half-maximal inhibitory concentration only for acetylcholinesterase. The aqueous preparation also protected cultured cells against an experimentally induced oxidative challenge.

This is a reason to investigate the chemistry beyond familiar cannabinoid labels. It is not proof that water-based cannabis products protect human brains, or that all constituents work better together.

Recent MyCannabis coverage of hemp bark and memory research raises a related question: could plant parts outside the usual focus on flowers yield useful experimental preparations? The broader lesson is that choosing the material and processing method is part of designing the intervention.

Whole Extracts Do Not Automatically Establish Synergy

If several ingredients affect different targets, their activities may complement one another. Demonstrating synergy requires showing that a combination performs better than expected from its individual components at comparable concentrations.

A useful follow-up would compare a chemically characterized extract with its separated fractions and a reconstructed mixture. That could reveal whether an effect depends on one dominant constituent, several additive contributions, or a particular interaction. This is a proposed research direction, not a result established by the review.

Standardization Could Make Early Findings More Valuable

The review identifies inconsistent chemical characterization as a barrier to reproducibility. If two laboratories use different mixtures under the same plant name, apparently conflicting results may reflect different interventions.

A 2025 review of herbal medicine standardization describes how metabolomics, the measurement of chemical constituents, can help create detailed fingerprints of plant preparations. Such fingerprints support comparisons between batches and make experimental materials easier to define.

For cannabis neuroprotection research, the implication is practical: a reproducible preparation may be more valuable than an unusually impressive result from a poorly described extract. Once the material is consistent, researchers can investigate why its effects change across doses, models, or laboratories.

Three questions would strengthen the next experiments:

• Can another laboratory reproduce the effect using the same chemically defined preparation?
• Do active constituents reach brain tissue at concentrations associated with the laboratory effect?
• Does treatment preserve function over time, alongside acceptable safety?

Reaching the Brain Is a Separate Research Problem

Cells in a dish encounter an extract directly. A medicine administered to a living organism faces absorption, metabolism, distribution, and elimination. The blood-brain barrier adds another selective boundary between circulating substances and brain tissue.

The authors therefore call for studies of toxicity, drug interactions, metabolic stability, and brain penetration. These are central questions about whether an experimentally active preparation can become useful.

MyCannabis’s coverage of an experimental CBD delivery system for brain injury offers a separate example of researchers treating delivery as part of the therapeutic problem. That work addresses a different condition and preparation; it does not validate the extracts in this review.

Likewise, research on CBD and post-seizure brain oxygen illustrates why researchers must specify the outcome they hope to improve. A change in oxygen availability, enzyme activity, or cellular survival answers a narrower question than whether a treatment prevents long-term neurological decline.

The Next Step for Cannabis and Brain Health

This review offers a constructive starting point: cannabis belongs among the plants with experimental signals worth investigating. Its contribution is to connect those signals with a clearer development agenda, including standardized chemistry, stronger disease models, safety evaluation, and eventual clinical testing.

It provides no basis for selecting a retail CBD oil or cannabis product to prevent dementia. An extract’s laboratory activity cannot be transferred to another formulation simply because both originate from Cannabis sativa.

The next decisive question is whether a reproducible cannabis preparation can reach the relevant brain tissue and preserve function in a well-designed disease model. Answering that would move the field beyond collecting promising observations toward building evidence that can guide treatment development.

References:

¹ Akoniyon, O. P., Olofinsan, K. A., Omotoso, B. R., Mbona, S. V., & Ntsapi-Combrink, C. (2026). Medicinal plants in South Africa with neuroprotective potential: A systematic review. South African Journal of Botany, 199, 621–635. https://doi.org/10.1016/j.sajb.2026.11.010