FoundationalConceptsNeuroscience

or unconscious, meaning never aware at all.)
Other drugs known to be associated with memory impairment
include cannabis (marijuana), cholesterol-lowering drugs (statins),
antiseizure medications, opioids, beta-blockers (prescribed for
hypertension), older-generation antihistamines (for example, diphen-
hydramine [Benadryl], chlorpheniramine), anticholinergics (used to
treat urinary incontinence), and tricyclic antidepressant medications.
Many of these medications are more frequently used in older indi-
viduals. It is likely that the regular ingestion of multiple prescribed
medications to treat various ailments results in significant side effects
of memory impairment and other kinds of mental confusion in the
elderly.
On the flip side, the term nootropic has been used to describe drugs
claimed to have improving effects on aspects of cognition, including
memory. Claims of improved memory have been made for caffeine,
nicotine, arecoline, and amphetamine. Chemicals that influence
acetylcholine neurochemistry have received particular attention:
phosphatidylcholine (also known as lecithin), the phospholipid
precursor to the synthesis of acetylcholine; and various inhibitors
of acetylcholinesterase, the enzyme responsible for breaking down
acetylcholine. In this latter category are several drugs used to reduce
memory loss associated with Alzheimer’s and other dementias:
donepezil (Aricept), tacrine (Cognex), rivastigmine (Exelon), and
galantamine (Razadyne; also present in certain plants, such as the
snowdrop [genus Galanthus], wild daffodil [Narcissus pseudonarcissus],
and red spider lily [Lycoris radiata]). How such drugs work to improve
memory is not known—is it an effect on memory per se, or is the
memory improvement secondary to an effect on enhancing attention,
for example?