Our brain lives in a symbiotic relationship with the bugs in our gut known collectively as the microbiome. Whatever we eat, they eat. In return, they help our brain function optimally in a variety of ways. During the past few years, it has become increasingly apparent that, in the absence of bacteria, humans would never have evolved to our current level of cognitive performance. Over the past billion years of evolution, brains have become profoundly dependent upon a wide range of chemicals produced by these gut bugs.

The gut microbiome plays a signiﬁcant role in both the progression and severity of Multiple Sclerosis (MS). MS is characterized by brain inﬂammation leading to degenerative changes that produce tremors, spasticity, and paralysis. In order to discover an effective treatment, scientists have used an animal model of MS called experimental autoimmune encephalomyelitis or EAE, that mimics conditions in a human MS patient’s brain.

Research using animal models has shown that cannabinoids are eﬀective treatment options against the inflammatory processes that underlie MS. The eﬃcacy of was described over 20 years ago when MS patients started claiming that marijuana decreased the incidence and severity of their symptoms.

In a recent study, combination of THC and eﬀectively reduced MS-associated tremors and spasticity in EAE animals. The combination therapy of THC and CBD also reduced the pro-inﬂammatory immune response that is normally seen in this mouse model of MS. It is important to note that treatment with THC alone or CBD alone were not eﬀective in attenuating these symptoms of EAE.

Examination of the colon revealed that the THC plus CBD treatment restored the gut microbiome that had been distorted by the EAE. The main effect was to reduce the abundance of Akkermansia muciniphila (A. muc). This finding is important because A. muc is involved in the exacerbation of symptoms in human MS patients.

The THC plus CBD treatment also produced additional changes in the gut metabolome, speciﬁcally increased levels of short-chain fatty acids, such as butyrate, that have an anti-inﬂammatory action in the body. Short-chain fatty acids play a very important role in regulating the inﬂammatory response and preventing autoimmune diseases such as MS by suppressing the production of pro-inflammatory proteins.

Most current treatments for MS act by regulating the immune response; unfortunately, these drugs are only eﬀective in 20–30% of patients. Thus, it is important to explore alternative pharmacotherapies such as medical marijuana.

© Gary L. Wenk, Ph.D., author of Your Brain on Food, 3rd Edition, 2019 (Oxford University Press).