Reversible Causes of Memory Loss
Not all memory loss is irreversible. Loss of memory can result from medication side effects, depression, certain medical conditions, and other controllable causes.
Memory Loss as a Medication Side Effect
Although older adults make up only 15 percent of the U.S. population, they receive more than 30 percent of all prescriptions written in this country. Unfortunately, as people age, natural changes within the body make adverse effects from medications more likely. For example, the kidneys may not remove drugs from the bloodstream as quickly as in younger adults, and drug metabolism in the liver may be slowed. In addition, a greater ratio of fat to muscle increases the time it takes to eliminate some drugs from the body.
Above all, older adults on average take more than five prescription drugs and three over-the-counter drugs at the same time, significantly raising the risk of drug interactions. In geriatric clinics, the most common cause of reversible dementia is an adverse reaction to medication. A class of medications called anticholinergics is known to cause cognitive problems in older people. Several commonly used medications are anticholinergics, including certain treatments for allergies, anxiety, asthma, depression, overactive bladder, pain, inflammation and Parkinson's disease. They are often an ingredient in "pm" sleeping pills sold over the counter. Some sedatives and sleep medications also can cause memory problems or even accelerate cognitive decline among people with Alzheimer's disease.
Alcohol is a common drug implicated in dementia. As is often the case with other drugs, the negative effects of alcohol on a person's intellectual abilities can frequently be reversed by abstinence. Chronic alcohol abuse, however, may lead to permanent damage; it is not clear whether this is due to the alcohol itself or to associated dietary insufficiency and head trauma.
Memory Loss Associated With Depression
The cognitive changes of dementia—impairment of memory, learning, attention and concentration—can also occur in people who are depressed, making the diagnosis of dementia more difficult. In fact, depression and cognitive decline often occur together.
A person is more likely to be suffering from depression than dementia if he or she has a prior history of psychiatric illness, a sudden onset of cognitive symptoms, difficulty sleeping, or a rapid decline in the ability to perform everyday activities. Because depression and dementia can be difficult to distinguish, a physician may suggest starting antidepressant therapy and then reassess the patient for dementia several months later.
Memory Loss Associated With Medical Conditions
A number of medical conditions can lead to memory problems, and in some instances, treating the underlying illness can reverse or reduce the memory deficit. These conditions include:
- Hormonal imbalances from thyroid disease or Cushing's disease (an overproduction of steroid hormones by the adrenal glands)
- Deficiencies of certain vitamins, especially vitamin B12
- Infectious diseases such as AIDS, syphilis, and chronic meningitis resulting from fungal infections or tuberculosis
- A brain tumor in the frontal or temporal lobe of the cerebral cortex
- Subdural hematomas (a collection of blood between the skull and the brain)
- Normal-pressure hydrocephalus (from excess fluid in the brain)
Some elderly people develop delirium in the hospital after surgery. The condition is characterized by drowsiness, inattention, disordered thinking, and other cognitive changes, and it increases the risk of developing lasting cognitive problems, including dementia.
There are many causes of delirium after surgery, among them medications (including sedatives, pain relievers, anticholinergic drugs, and anesthesia), low levels of oxygen, blood sugar fluctuations, the physical stresses of surgery, dehydration, and overhydration. It is likely that many people who develop delirium were already experiencing the early brain changes of dementia and that the stress of the treatment of a new illness then triggered the delirium.