When acetylcholine receptors are blocked by scopolamine, healthy young people find it harder to learn and remember, especially in a distracting environment, suggesting a mechanism through which cholinesterase inhibitors may improve symptoms of mild-to-moderate Alzheimer disease-related dementia, according to an article in the February issue of Behavioral Neuroscience.

Of 28 participants, 12 received injections of scopolamine. Afterward, the researchers measured how well participants learned new pairs of words, a common memory test. Two other groups of 8 participants each served as controls who were tested on learning but were given either no drugs or the medicine glycopyrrolate to mimic the dry mouth produced by scopolamine. Glycopyrrolate is a synthetic anticholinergic that crosses the blood-brain barrier more slowly and incompletely compared with scopolamine.

In the experimental group, memory for word-pairs learned after scopolamine administration suffered significantly but memory for word-pairs learned immediately before injection was spared. Scopolamine also made it harder to learn when stimuli overlapped, creating a proactive interference with learning ? a condition more closely resembling everyday life. The researchers also found that even glycopyrrolate produced subtle but measurable effects on memory and learning.

According to the authors, the findings suggest that anticholinergics might serve as a kind of cognitive ‘stress test’ for elderly patients who have an underlying dementia in its earliest stages, unmasking symptoms that would be hard to detect otherwise. At the same time, they added “>From a cognitive health standpoint, the chronic use of medications with anticholinergic effects by elderly individuals, especially if they’re cognitively impaired, would be highly discouraged. Use of such medications, particularly during waking hours, would be expected to interfere with acquisition and future recall of new and, especially, related memories.”