4.6 Medicines Used to Treat Dementia

Cholinesterase inhibitors and N-methyl-d-aspartate are the two kinds of medications
that have been approved to treat Alzheimer’s disease (NMDA).

• Cholinesterase Inhibitors

The neurotransmitter acetylcholinesterase is reversibly bound and inactivated by the cholinesterase inhibitors, lengthening the duration it spends in the synaptic cleft. Donepezil, galantamine, and rivastigmine are the three cholinesterase inhibitors that have received FDA approval.

Following reports of significant liver toxicity, Tacrine—the first cholinesterase inhibitor to receive FDA approval—was taken off the market. Cholinesterase inhibitor side effects are typically moderate, well tolerated, and pass in 1 to 2 weeks. Common gastrointestinal side effects include vomiting, nausea, and diarrhea.

• NMDA Receptor Antagonist

Memantine, the sole FDA-approved NMDA receptor antagonist, works by lowering neuronal calcium ion influx and the excitation and toxicity it brings with it. It is recommended for mild to severe Alzheimer’s disease.

Moreover, memantine generally has a better side-effect profile than cholinesterase inhibitors. Clinical investigations have shown a higher tolerance and fewer side effects.

That said, despite the benefits, the medications can offer, the possibility of negative consequences should be taken into account by practitioners when choosing a cognitive enhancer.