Alzheimer's disease is a progressive neurological disorder that initially causes patients to have short-term memory loss, then progresses to an inability to use common, everyday objects and tools, and ultimately results in death from complications such as malnutrition and infection. There is no cure for Alzheimer's as of 2010; according to the medical reference UpToDate, patients generally die within eight years of receiving a diagnosis. Several treatments have been approved to help slow the progression of Alzheimer's disease, though their long-term benefit is unclear.
Donepezil
According to the textbook "Goodman & Gilman's The Pharmacological Basis of Therapeutics," a significant deficiency in acetylcholine, an important neurotransmitter, has been found to be one of the hallmarks of Alzheimer's disease. Several of the Alzheimer's disease treatments that have been approved by the FDA work by blocking an enzyme called acetylcholinesterase, or AChE. One of these AChE inhibitors, as the class of drugs is known, is called donezepil. By blocking AChE, donepezil--also known by its brand name Aricept--prevents the breakdown of acetylcholine, so that more of this critical substance is available within the brain. According "Goodman & Gilman's The Pharmacological Basis of Therapeutics," patients taking donepezil show slight improvement in scores on tests of cognitive ability. In addition, the ability to give the medicine only once daily is an advantage of this AChE inhibitor. Side effects include nausea, vomiting or diarrhea, as well as insomnia, headaches and high blood pressure. An important consideration with donepezil--indeed with all the medications available to help treat Alzheimer's disease--is that while it may help with certain symptoms such as memory loss, it cannot prevent the eventual loss of mental abilities.
Rivastigmine
Rivastigmine, or Excelon, is an AChE inhibitor that works similarly to donepezil. A review study published in 2009 in "Cochrane's Database of Systematic Reviews" looked at the results of nine studies involving over 4,700 patients. The reviewers concluded that rivastigmine may be helpful for patients with Alzheimer's that is in the mild to moderate stages. One potential disadvantage of rivastigmine is that patients need to take this medication twice daily. Side effects include insomnia, diarrhea, nausea, vomiting, headaches and dizziness; a lack of appetite may also occur. Taking rivastigmine with food may help to decrease the nausea patients may experience when taking the medication.
Memantine
The pharmacology reference MicroMedex describes memantine as a central nervous system agent that blocks certain cell receptors called the NMDA receptors. MedlinePlus reports that while this medication may help patients with Alzheimer's do their daily activities a bit more easily, it does not slow the progression of Alzheimer's disease. Side effects of memantine include fatigue, headache and dizziness. It can also cause confusion, which is a concern because people with Alzheimer's also experience this symptom. According to MedlinePlus, constipation and vomiting may occur as well. Rarely--in 3 percent of cases, as reported in MicroMedex--patients may suffer from hallucinations.
References
- MedlinePlus: Memantine
- MedlinePlus: Donepezil
- "Goodman & Gilman's The Pharmacological Basis of Therapeutics;" Laurence Brunton, et al.; 2006
- "Cochrane Database Systematic Reviews;" Rivastigmine for Alzheimer's disease; J. Birks, et al.; April 2009
- MicroMedex: Memantine
