Herbal Neurotherapeutics for Cognitive Disorders: Integrative Mechanisms Linking Neurotransmitter Systems, Neurodegeneration, and the Gut-Brain Axis

Abstract

Cognitive disorders, including Alzheimer’s disease, Parkinson’s disease, schizophrenia, depression, and vascular dementia, are associated with dysregulation of neurotransmitter systems, including acetylcholine, dopamine, serotonin, glutamate, and γ-aminobutyric acid (GABA). These disorders are increasingly recognized as multifactorial conditions involving oxidative stress, neuroinflammation, mitochondrial dysfunction, synaptic impairment, blood–brain barrier disruption, metabolic imbalance, and gut–brain axis dysregulation. Current pharmacological therapies may provide symptomatic relief; however, their clinical benefits are often limited and associated with adverse effects. Herbal medicines have gained increasing attention as potential complementary approaches for cognitive support and neuroprotection. Preclinical evidence and emerging clinical studies suggest that herbal bioactive compounds may exert neuroprotective effects through antioxidants, anti-inflammatory, and neurotransmitter-modulating mechanisms. Medicinal herbs such as Bacopa monnieri, Withania somnifera, Ginkgo biloba, Glycyrrhiza glabra, Moringa oleifera, and ginseng have shown potential cognitive benefits in experimental models and selected human studies. Advanced delivery systems, including nanoparticles and phytosomes, may further improve the bioavailability and brain-targeting efficiency of herbal compounds. However, current clinical evidence remains heterogeneous and limited by insufficient standardization, small sample sizes, and short study durations. Further large-scale clinical studies and standardized safety assessments are essential before herbal neurotherapeutics can be widely applied in cognitive and neurological disorders.