As of early 2008, the U.S. Food and Drug Administration (FDA) had approved five drugs for use with Alzheimer’s disease: memantine (Namenda), galantamine (Razadyne), rivastigmine (Exelon), donepezil (Aricept), and tacrine (Cognex).

In most cases, the drugs prevent the breakdown of acetylcholine in the brain, thereby increasing the efficiency with which neurons communicate with each other. These drugs can modestly increase cognition and improve the ability to perform normal activities of daily living.

Side effects accompany the use of each drug, the most common of which are diarrhea, nausea, and vomiting. Tacrine has an additional side effect of some concern, promoting an increase in the liver enzyme alanine aminotransferase (ALT).

Patients taking tacrine must have a weekly blood test to monitor their ALT levels.Estrogen, a female sex hormone, has been widely prescribed for post-menopausal women to prevent osteoporosis.

Several preliminary studies have shown that women taking estrogen have lower rates of AD, and those who develop AD have a slower progression and less severe symptoms.

Preliminary studies suggested a reduced risk for developing AD in older people who regularly use nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, ibuprofen (Advil), and naproxen (Aleve), although not acetaminophen.

A 2001 study reported that those subjects who used NSAIDs for at least two years were up to 80% less likely to develop Alzheimer’s. Later studies have not confirmed this original finding, however, and there was as of 2008 no good reason to recommend the use of NSAIDs in the treatment of AD.

Selegiline, a drug used in the treatment of Parkinson’s disease, appears to slow the development of AD. Selegiline is thought to act as an antioxidant, preventing free radical damage.

However, it also acts as a stimulant, making it difficult to determine whether the delay in onset of AD symptoms is due to protection from free radicals or to the general elevation of brain activity from the stimulant effect.

Psychiatric symptoms, such as depression, anxiety, hallucinations (seeing or hearing things that aren’t there), and delusions (false beliefs) may be treated with drugs if necessary.