Is It Dementia?
Forgetfulness: Some older people become very forgetful. But other mental functions (thinking, understanding, communicating, and controlling behavior) seem unaffected. This type of memory loss is sometimes called mild cognitive impairment or benign senescent forgetfulness. People who have it often worry that this forgetfulness is the first sign of dementia, particularly Alzheimer's disease. For about half of them, their worst fears come to pass, as other signs of Alzheimer's disease very slowly develop over the next 3 to 5 years.
Many other older people have only a very slight problem remembering things, but they also have slight problems with other mental functions. In these people, the problems are often so slight that they are not noticed, and the problems do not seem to worsen. This condition is called age-related cognitive impairment. Its effects are much less drastic than those of dementia. And unlike dementia, it does not affect the ability to function.
Depression: Some older people become forgetful, confused, disoriented, and distracted because they are depressed. In such cases, depression may be mistaken for dementia. Often, people who are depressed are bothered by their forgetfulness. In contrast, people who have true dementia often deny any forgetfulness. Treating depression usually restores mental function. However, some people have dementia and depression. For them, treating the depression may improve (but not restore) mental function.
Other disorders: Several disorders can cause some of the symptoms of dementia. These disorders are sometimes mistaken for dementia. Examples are delirium, vitamin deficiencies (especially vitamin B12 deficiency), and an underactive thyroid gland (hypothyroidism)—disorders that are common among older people. Treating these disorders may partly or completely restore mental function.
In some disorders, brain tissue is damaged, sometimes resulting in symptoms similar to those of dementia. But symptoms do not worsen as they do in dementia. These disorders include head injuries and sudden stopping of the heart's pumping (cardiac arrest), which deprives the brain of oxygen. Radiation therapy to the head as treatment for a brain tumor may damage brain tissue and impair mental functions, especially memory. Many months or years after treatment, radiation therapy occasionally results in symptoms that resemble those of dementia.
