Memantine and its role in parkinsonism, seizure, depression, migraine headache, and Alzheimer’s disease

Alzheimer’s disease (AD) is a neurological disorder characterized by mental and behavioral changes that develop progressively with a decline in brain function. Dysfunctions in glutamatergic and cholinergic pathways, along with an increased concentration of beta-amyloid protein (Aβ), lead to synapses that are full of phosphorylated protein. These changes result in several pathological, biochemical, cellular, and molecular alterations that increase neural excitation directly or indirectly at the neural level, affecting the synapse, axons, signal transmission, and all parts of neurons. All these alterations, with continuous excitatory effects, eventually lead to neural loss and degradation due to stimulation of the immune response. However, memantine is a non-competitive antagonist of N-methyl-D-aspartic acid (NMDA) glutamatergic receptors of moderate affinity and voltage-dependent that blocks the effects of pathologically elevated glutamate tonic levels, which can lead to neuronal dysfunction. Memantine has shown improvement in cognition, global clinical status, activities of daily living, and behavioral disturbances in moderate and severe AD. In this review, we will discuss the effects of memantine use and side effects, as well as its application in treating other diseases or pathological conditions with the prospective use of memantine or an alternative. Memantine is generally well-tolerated, and the most common adverse reactions are vertigo, headache, and hallucinations, which are usually mild