Is it forgetfulness or dementia?

Regardless of age, everyone experiences occasional episodes of forgetfulness. Many people fear that a growing number of such lapses are a sure sign of Alzheimer's, but there are important differences between simple forgetfulness and dementia (see Table 1). Experts now recognize a third state called mild cognitive impairment, which falls in between normal memory function and dementia. People with mild cognitive impairment are at increased risk of developing dementia.

Table 1: Normal aging or dementia?
Physicians often use a chart like this to help differentiate between normal aging and dementia.
Normal aging	Dementia
Preserved independence in daily activities	Critical dependence on others for key daily living activities
The person complains of memory loss but can provide considerable detail regarding incidents of forgetfulness	The person complains of memory problems only if specifically asked; cannot recall instances where memory loss was noticeable
The individual is more concerned about alleged forgetfulness than close family members are	Close family members are much more concerned about incidents of memory loss than the individual
Recent memory for important events, affairs, and conversations is not impaired	Recent memory for events and ability to converse are both noticeably impaired
Occasional word-finding difficulties	Frequent word-finding pauses and substitutions
Person does not get lost in familiar territory; may have to pause momentarily to remember way	Person gets lost in familiar territory while walking or driving; may take hours to return home
Individual operates common appliances even if unwilling to learn how to operate new devices	Person cannot operate common appliances; unable to learn to operate even simple new appliances
No decline in interpersonal social skills	Loss of interest in social activities; socially inappropriate behaviors
Normal performance on mental status examinations, relative to the individual's education and culture	Below-normal performance on mental status examinations in ways not accounted for by educational or cultural factors
Source: Diagnosis, Management and Treatment of Dementia: A Practical Guide for Primary Care Physicians (American Medical Association).

Normal forgetfulness

Normal forgetfulness is neither progressive nor disabling. Such memory problems are likely to surface when you're under stress, fatigued, ill, distracted, or overloaded. Typically, you remember the forgotten information later. Like most people, you probably rely on written reminders and other memory-jogging techniques to overcome this kind of forgetfulness.

A certain increase in forgetfulness seems to be a normal by-product of aging and is perhaps a result of changes in the brain that begin around age 50, such as a gradual loss of receptors on brain cells and a decline in certain neurotransmitters. Blood flow to the brain cells falls after age 30, and this decline could also impair memory. Researchers have found that half to two-thirds of people age 50 or over have some degree of memory loss.

Researchers disagree over how much deterioration is normal. Comparisons of younger and older people's scores on memory, learning, and intelligence tests suggest that mental sharpness declines only slightly with age. But whether such comparisons are valid is questionable because timed tests may favor the younger person. The older person's information processing is a little slower: In one study, elderly people took 20–40 milliseconds longer than younger people to detect gaps in circles.

Thus, the lower scores of older persons may simply reflect a slowing of their responses, not a reduction in their mental sharpness. People may require more time and effort to learn new information as they age, but once they've learned it, they retain it as well as younger people. In practical terms, slightly slower thinking is not necessarily a disadvantage. It may actually reflect more thorough reasoning and result in fewer mistakes.

It's important to note, though, that memory loss isn't inevitable. There are many things you can do to preserve or sharpen your memory, including learning memory-enhancing techniques, reducing stress, and improving your organizational techniques (for example, always writing down appointments or having a designated spot for belongings such as keys and eyeglasses). It's also important to regularly challenge your mind with activities such as reading, doing crossword puzzles, playing chess, or taking classes. Experts believe that these kinds of activities help build and maintain synapses, the small gaps between neurons that enable them to communicate with one another.

Much age-related mental decline is due to poor vision or hearing, cardiovascular disease, diabetes, sleep disturbances, alcohol abuse, depression, or medications that interfere with the mental processes. Addressing these conditions can also make a difference. In the final analysis, changes people see in themselves or a relative are far more likely to be signs of some other health problem, not early dementia.

Mild cognitive impairment

Mild cognitive impairment (MCI) is considered a transitional state between normal forgetfulness and dementia. At least one cognitive (thinking) domain — usually memory — is below normal or in decline. When memory is affected, the condition is called amnesic MCI. Although some people with MCI remain stable or even improve, studies show that the majority, especially those with amnesic MCI, eventually develop dementia.

Researchers who examined brain tissue removed during autopsies have provided evidence that certain telltale anatomical changes may underlie this progression. As reported in the Archives of Neurology in 2006, the researchers found that the brains of people with amnesic MCI have more neuritic plaques (clumps of degenerating neurons) and neurofibrillary tangles (abnormal twisted fibers inside neurons) than normal, but not as extensive as the pathology characteristic of Alzheimer's. About 10%–15% of people with MCI progress to dementia each year. MCI becomes more common with age and affects 3%–22% of people over age 65.

A person who has MCI is able to carry on daily activities without difficulty, but a particular subset of cognitive skills may be diminished. In particular, someone with MCI may show some of the following signs:

Increasing difficulty with memory or, in some cases, subtle problems in other cognitive domains, such as language, attention, spatial skills, and problem solving

Confirmation of impairment on neuropsychological tests, often manifesting as difficulty with learning and delayed recall of information compared with others of the same age and education level. In some cases, memory is normal but is less reliable than it used to be.

Dementia

With dementia, memory loss is severe enough to interfere with someone's ability to function socially and at work. The most common type of dementia is Alzheimer's disease, but there are many other types, including frontotemporal lobar degeneration, dementia with Lewy bodies, and vascular cognitive impairment, which is caused by multiple strokes that interrupt blood flow to the brain. These are some signs of dementia:

Intellectual function has declined from a previous level. This change in mental ability differentiates dementia from mental retardation.

The person is aware and alert, which differentiates dementia from delirium.

More than one type of thinking is affected. In addition to memory, at least one of the following also is impaired: personality, abstract thinking, judgment, use of language, the ability to perform complex physical tasks, or the ability to recognize objects or people. Known as global cognitive impairment, this characteristic distinguishes dementia not only from mere forgetfulness but also from such conditions as amnesia (memory loss only) and speech deficits (caused by stroke, for example).

Review Date: 2007-01-01

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