Information about Controllable Causes of Dementia

Memory loss 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 12 percent of the U.S. population, they receive about 30% 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. Commonly used medications called anticholinergics are known to cause cognitive problems in older people. These include treatments for:

  • allergies
  • anxiety
  • asthma
  • depression
  • heart failure
  • overactive bladder
  • pain
  • inflammation
  • Parkinson's disease

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. Fortunately, as is often the case with other drugs, the negative effects of alcohol on intellectual abilities can frequently be reversed by abstinence, although chronic alcohol abuse may lead to permanent damage.

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 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 reassessing 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)
  • infectious diseases such as AIDS, syphilis, and chronic meningitis resulting from fungal infections or tuberculosis
  • 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)
  • deficiencies of certain vitamins, especially vitamin B12

In addition, 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. It is not known what causes delirium after surgery, but potential contributing factors include:

  • low levels of oxygen
  • blood sugar fluctuations
  • the physical stresses of surgery
  • inflammation
  • effects of sedatives, pain relievers, or anesthesia

Publication Review By: Peter V. Rabins, M.D., M.P.H.

Published: 09 Mar 2011

Last Modified: 28 Jan 2015