Cholinesterase inhibitors

One effect of lost nerve cells is lower levels of a chemical messenger called acetylcholine. This messenger is important for memory, language, judgment and other thinking skills. Cholinesterase inhibitors prevent the breakdown of acetylcholine, making more of the chemical messenger available to healthy nerve cells.

Over time, the continued loss of brain cells means that not enough of the messenger chemical is available.

Side effects of cholinesterase inhibitors can include nausea, diarrhea, loss of bladder control, muscle cramps, muscle twitching and weight loss. If taken at night, the medicine may cause vivid dreams. Starting treatment at a low dose and working up to a higher dose can help lessen side effects. Taking these medicines with food also might help lessen some side effects.

People with certain conditions that cause irregular heartbeats can't take cholinesterase inhibitors.

Three cholinesterase inhibitors are commonly prescribed:

• Donepezil (Aricept) is approved to treat all stages of the disease. It's taken once a day as a pill.
• Galantamine is approved to treat mild to moderate Alzheimer's disease. It's taken as an extended-release pill once a day or as a pill or liquid twice a day.
• Rivastigmine is approved for mild to moderate Alzheimer's disease. It's taken as a pill twice a day. A rivastigmine skin patch (Exelon) that's approved to treat all stages of Alzheimer's disease is changed daily.