ABSTRACT
Alzheimer’s disease (AD) is a degenerative brain disorder that manifests as a progressive deterioration of the memory and mental function – a state of mind commonly referred to as “dementia” – and causes changes in personality and behavior. Major pathological hallmarks of AD are characterized by deposition of abnormal amyloid-β protein plaques, the formation of neurofibrillary tangles of tau proteins, and a decline in cholinergic neurotransmission in the brain. During the past decade, a significant growth in the incidence of AD has stimulated research into the search for new medicines. One of the major clinical advances in the treatment of AD have been the use of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors to increase the ACh level in the brain, although cholinergic compounds with nicotinic and muscarinic agonist properties have also attracted some interest. At present, there are very few pharmaceuticals available to treat AD, with most of the available treatments restricted to delaying the progression of symptoms and achieving short-term symptomatic relief. Medicinal plants represent a reservoir of untapped resources of natural medicines and potential sources of natural AChE inhibitors. The structural diversity of phytoconstituents makes them a valuable source of novel lead compounds in the quest for drugs to treat AD. Medha Rasayana is a group of Ayurvedic nootropic drugs, which enhance cognitive functions and improve memory. Medha Rasayanas are Ayurvedic supplements, which improve the power of acquisition, retention and recollection (the three stages of memory formation). They can improve cognition, intellect, and learning skills. Additionally, these plants also boost immunity. These herbs exert a prominent effect on the brain. Ayurveda provides a list of herbs known for their nootropic activity as well as for their multifunctional value to treat various conditions. The present chapter is a review to collate current knowledge on the pharmacological properties, major chemical constituents, therapeutic actions, preclinical studies, safety, and possible mode of action of the selected Ayurvedic herbs. Concurrently, it opens up avenues for further research and standardization work on nootropic herbs.
