Steroids, benzodiazepines, and medications with anticholinergic properties are among the commonly used medications that can cause memory loss.
Steroids like hydrocortisone and prednisone are used to treat severe asthma and autoimmune diseases like rheumatoid arthritis and systemic lupus erythematosus (SLE or lupus). Many skin creams and ointments also contain steroids, but these are not absorbed in sufficient quantities to affect the brain. Steroids work by suppressing the body's natural immune response against bacteria, viruses, and toxins, and this helps in diseases where there is a wayward, self-destructive immune response. Steroids have a number of side effects, including stomach ulceration and weakening of bone structure (osteoporosis). In high doses, steroids can affect the brain, causing memory loss, confusion, and even psychosis. But subtle effects—particularly low-grade depression, anxiety, and memory loss—are far more common.
You may recall Sapolsky's theory that high levels of circulating steroids causing hippocampal neuronal loss lead to memory deficits, though whether this occurs clinically remains unclear. If you're on steroids and feel that your memory has begun to decline, report this symptom to your doctor, who may choose to stop the medication or lower the dose.
Benzodiazepines comprise another class of medications that can cause subtle memory loss. From the 1960s to the 1980s, whenever patients seemed anxious or complained about sleeplessness, physicians routinely prescribed benzodiazepines. Over time, it became clear that benzodiazepines like diazepam (Valium) and flurazepam (Dalmane, "mother's helper'' for sleep) had addictive properties. In the United States, many states have passed regulations that place benzodiazepines under the class of controlled substances, thus making them more difficult to prescribe. Nevertheless, most doctors still prescribe them, although on a more limited basis, because the other available antianxiety medications are not as effective.
Benzodiazepines can reduce concentration and cause mild memory loss. In elderly people, benzodiazepine use can lead to confusion, unsteady gait, and falls. Benzodiazepines need to be gradually tapered to reduce the risk of severe panic or seizures that can occur after sudden withdrawal.
Acetylcholine is central to memory and attention, and it is present in high concentrations in the hippocampus and neighboring regions.
Therefore, medications with antiacetylcholine, or anticholinergic, properties can produce cognitive deficits that include memory loss. As with benzodiazepines, high doses can result in confusion and disorientation, though this occurs mainly in people who overdose. A variety of medications have anticholinergic properties, including older antidepressants like imipramine (Tofranil) and amitriptyline (Elavil), as well as antipsychotics like chlorpromazine (Thorazine), thioridazine (Mellaril), and olanzapine (Zyprexa). Acetylcholine also increases muscle activity and secretions in the gastrointestinal tract and bladder, so anticholinergics can cause the opposite: dry mouth, constipation, and urinary retention. As with steroids and benzodiazepines, if you're being prescribed an anticholinergic medication and have begun to experience memory loss, you should report this to your doctor and ask about stopping it or taking another type of medication.
Among the medications listed here, the research data on barbiturates, phenytoin, antidepressants with anticholinergic properties, benzodiazepines, narcotics, lithium, and cimetidine are fairly convincing, but there is less evidence to show that antihypertensives and digitalis cause significant cognitive deficits. Diphenhydramine (Benadryl), which is widely used, has antihistaminic and anticholinergic properties, both of which predispose people to cognitive impairment, including memory loss.
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