Cognitive impairment is a serious explanation for disabling illness amongst older adults. A brand new paper published within the journal Brain Disorders explores available evidence that medicinal plants may help improve cognitive function by reducing brain inflammation.

Study: Reversing memory/cognitive impairment with medicinal plants targeting inflammation and its crosstalk with other pathologies. Image Credit: Antonova Ganna / Shutterstock.com

Introduction

Various neuroinflammatory conditions present with impaired memory and cognition, including Alzheimer’s disease (AD), vascular dementia, Huntington’s disease, multiple sclerosis (MS), in addition to traumatic brain injury (TBI) and stroke. Pollution-induced brain injury, infectious meningitis, and brain damage resulting from infections like malaria or coronavirus disease 2019 (COVID-19) even have inflammation as their basis of toxicity.

There may be some evidence that inflammation is accountable for most diseases involving cognitive impairment. In actual fact, for MS, all effective therapeutic interventions are anti-inflammatory of their mechanism of motion.

Almost any neurological, neurodegenerative, traumatic damage or toxic insult to brain tissues involved in memory generation, may result in memory deficits.”

Previous research has identified over 1,300 plants that contained potentially relevant bioactive compounds that would heal neurodegeneration. A lot of these plants exhibited activity against 15 potential drivers of AD, including oxidative stress, mitochondrial dysfunction, hyperphosphorylated tau protein, and soluble amyloid, in addition to gut dysbiosis, reduced estrogen levels, and impaired cholinergic neurotransmission.

What did the study show?

A complete of 251 plant species with documented memory improvement effects were identified for the present evaluation, 94% of which have anti-inflammatory activity. This commentary supports the hypothesis that all these protective plants act by combating each systemic and neuroinflammation, along with suggesting that inflammation underlies AD.

Some plants with reported memory improvement effects include neem, grapes, papaya, citrus plants, walnuts, mango, mint, onion species, including garlic, ginger, and cinnamon.

Furthermore, over 120 of the species had specifically anti-neuroinflammatory activity, with over 100 showing each improvement of cognitive and memory function and inhibition of neuroinflammation. Many of the trials were preclinical, thus indicating the necessity for more human studies.

These plants produced their effects through the downregulation and inhibition of assorted signaling pathways mediated by pro-inflammatory chemicals similar to nuclear factor κB (NF-κB), C/EBPβ, extracellular signal-regulated kinase (ERK)/c-Jun N-terminal kinases (JNK), p38 mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/ protein kinase B (Akt), Notch and Wnt, in addition to the inflammatory molecules triggered by them.

Sustained hyperactivation of those pathways would produce persistent neuroinflammation, thereby activating the astrocytes and microglia. Subsequently, molecules like glutamate, reactive oxygen species (ROS), and reactive nitrogen species (RNS) may be released and ultimately contribute to neuronal death.

Activated microglia can even phagocytose live neurons resulting from the abnormal expression of cell surface molecules that induce the sort of activity. Indirect neuronal death by microglia could also occur through apoptosis resulting from the discharge of proteolytic aspects like cathepsins, in addition to through tumor necrosis factor (TNF) activation of glial cells.

These processes can ultimately result in memory loss and impaired cognition, each of that are resulting from the lack of neurons. Plants like those of the brassica family, including cabbage, broccoli, kale, brussels sprouts, and collard greens, in addition to cashew plants, grapes wealthy in resveratrol, and pomegranates, have all been reported to inhibit the NF-κB pathway.

Each plant species was related to the capability to inhibit multiple pathways, including well-known plants like ginseng and less-known species similar to sea ragweed.

Many of the identified plants also reduced the severity of other inflammatory disease processes and their interactions with one another. This led to reduced oxidative stress following treatment with plants like Brahmi (water hyssop) and the pigeon pea. Red sage and the oil palm also led to decreased levels of beta-amyloid and tau protein.

Toxic metal chelation was enhanced by silymarin and epigallocatechin gallate (EGCG). The anti-microbial activity was also related to quite a few plants similar to coconut and fig plants, mango, onion, drumstick plants, and pomegranates, all of which also produced favorable changes in gut microbiota.

Many plants also led to autophagy, while mango and tamarind plants were reported to advertise neurogenesis. Reduced acetylcholinesterase (AChE) activity was observed with vanillin from the vanilla plant, in addition to the drumstick tree.

Microglial phagocytosis also improved, thereby allowing higher clearance of cell debris like amyloid. Reduced astrogliosis, or reactive astrocyte activation, was also observed following treatment with these plants.

Taken together, these various compounds provide exciting prospects within the seek for phytochemicals with enhanced therapeutic bioactivity.”

What are the implications?

The present study reports the wide-ranging effectiveness of many medicinal plants in inhibiting neuroinflammation and its accompanying pathologies. Furthermore, these plants were found to enhance memory and cognition, in addition to exhibit antioxidant and anti inflammatory activity.

Despite the promising advantages related to these plants, clinical trials are needed to ascertain that these plants can goal neurons within the human brain and discover the precise points of neuroinflammatory inhibition. Imaging, for instance, could yield considerable data on how all these plants affect inflammation and its associated pathologies over time and in several parts of the organism.  

Advanced technologies can even be needed for higher neuroimaging and plasma testing to permit researchers to guage the effectiveness of plant chemicals on brain targets and in inhibiting inflammation and accompanying pathological processes. This kind of research could also help understand how inflammation causes or contributes to memory and cognitive loss.

[This could eventually lead to] a much needed and crucial breakthrough of data, to boost the prospect of reversing memory impairment and dramatically improve patient quality of life.”