An acetylcholinesterase inhibitor medication taken to improve cognitive function. At present, this drug has U.S. Food and Drug Administration (FDA) approval in the United States for treating dementia of Alzheimer’s disease and is in clinical trials to explore its effectiveness for treating vascular (multiinfarct) dementias. Galantamine and other acetylcholinesterase inhibitors appear to improve memory and cognition in some people who have dementia of Parkinson’s disease as well according to a number of published case reports. Not all people with dementia who take these drugs, whether the dementia’s origin is Alzheimer’s or Parkinson’s, experience cognitive improvement. Researchers do not know why some people respond and others do not.
As do other drugs in this classification, galantamine works by preventing the action of acetylcholinesterase, an enzyme in the brain that metabolizes acetylcholine. This neurotransmit-ter plays a key role in cognitive functions and becomes depleted in people who have Alzheimer’s disease. Such a depletion does not affect people with Parkinson’s disease unless they also have Alzheimer’s, as is the case for about one in four. The depletion of dopamine, the neurotransmitter of functions in the basal ganglia and other parts of the brain related to movement, does affect the balance between dopamine and acetylcholine; some researchers believe that their imbalance contributes to Parkinson’s dementia and perhaps explains why acetylcholinesterase inhibitors can be effective. Other researchers believe the connections between Alzheimer’s disease and Parkinson’s disease are more intricate and complex than scientists presently understand and that these drugs are effective for people who have either condition because of these connections.
There is some evidence that galantamine also activates nicotinic receptors in the brain, which are selected acEtylcholinE receptors in certain parts of the brain that also are receptive to nicotine. When nicotine binds with these receptors, it produces an intensified effect that enhances memory and other cognitive functions. Although galantamine does not contain nicotine, it appears capable of binding with nicotinic receptors in the same way. This mimics the action of nicotine, a stimulant chemical that exists in small amounts in a number of foods and in much larger amounts in tobacco.
Galantamine derives from a substance first extracted from the bulbs of certain daffodils and lilies and in the United States is sold as a prescription drug under the brand name Reminyl. Side effects that can arise from taking galantamine include dizziness, nausea, vomiting, and, in some people, weight loss (believed to be a function of galantamine’s activation of nicotinic receptors).