Contributor: Gene D. Cohen
Aging may variably affect cognition, memory, intelligence, personality, and behavior. However, many changes in mental health are difficult to attribute to aging per se; they are often the result of disease. Decreases in mental capacity or performance (eg, cognition, behavior) that are viewed as age related may instead be due to treatable illnesses (eg, depression, hypothyroidism). A rapid decrease in cognition is almost always due to disease.
The effects of aging on mental health may also be related to socioenvironmental factors, including the care setting. For example, the prevalence of psychiatric disorders is 15 to 25% among persons aged 65 living in the community and 27 to 55% among those in the hospital. Psychiatric disorders are a primary or secondary diagnosis in 70 to 80% of nursing home residents; in one study, 94% of nursing home residents had a psychiatric disorder. Brain disorders causing dementia (most commonly, Alzheimer's disease (see page 365)) affect about 10% of persons aged 65 and at least 25% of those aged 85.
With age, cognitive functions may remain stable or decline. In general, cognitive functions that remain stable include attention span, everyday communication skills, many language skills (eg, syntax), the ability to comprehend discourse, and simple visual perception. Vocabulary can improve even in persons in their 80s. Cognitive functions that decline include selective attention, naming of objects, verbal fluency, complex visuospatial skills, and logical analysis. Learning complex new tasks and foreign languages becomes more difficult with age.
Age-related memory changes vary depending on the type of memory function; the ability to acquire, store, and retrieve new memories may be reduced, whereas the ability to retrieve memories that have been stored and consolidated over long periods remains stable. Reduced memory performance can be improved using adaptive strategies.
Intellectual abilities peak during the 30s, plateau throughout the 50s and 60s, and variably decline during the late 70s. Elderly persons may have difficulty with activities requiring a quick reaction time or high degree of precision, although they maintain the ability to understand their situation and learn from new experiences. Reduced reaction time can be compensated for by allocating more time for tasks.
Depression, anxiety, and other psychiatric disorders can also interfere with cognition. Pseudodementia (eg, depression or psychosis mimicking dementia (see page 363)) is an extreme form of such interference.
Personality remains stable with age. However, whether behavior also remains stable with age is debated. Usually, behavioral and psychologic adaptiveness continues and does not normally regress or become rigid. Increasingly exaggerated, maladaptive, and unmodifiable behaviors or traits (see page 371) may represent psychologic or neurologic problems and not normal aging.
In general, frail or disabled elderly persons are more cautious than younger persons, especially when risk taking involves a predictable and constant payoff (eg, they may not fly standby for a routine visit to family members, even if it increases savings); however, the elderly are not more cautious if the payoff appears to exceed the degree of risk (eg, they may fly standby if it represents the only chance to visit family members for a special occasion). Excessive cautiousness in elderly persons may signal underlying anxiety or a related physical disorder; however, excessive cautiousness in frail or disabled persons may reflect good judgment.
The elderly usually adapt to the concept of impending death after becoming aware of it (sometimes suddenly) during middle age. Although the elderly often think about death, they fear death less than other age groups. Thoughts or conversations about death are more common among the elderly, who likely have peers and relatives who have died or are dying.
A terminal illness, an underlying depression, or other emotional conflict predisposes certain elderly persons to anxiety about death and, in some cases, can lead to despondency. The ability to cope with such stress is maintained or improved with age.
Elderly persons who experience significant losses (eg, loss of a spouse or partner, economic status, physical health, or overall independence) often have diminished self-esteem and depression. A loss of control over one's life may be so disturbing that it may result in physical symptoms that represent maladaptive efforts to control other persons, gain attention, or signal for help. Vague physical decline does not always indicate physiologic aging or the subtle progression of underlying physical illness. In one study of depressed men and women > 60 years, physical complaints were reported by > 60%. The nature and rate of physical decline in a patient who is clinically depressed can reflect the will to live or die.
Many elderly persons in the community have the same degree of physical disability as those in nursing homes; the differences appear to be related to the availability of family members, the availability of other types of social support, and coexisting psychiatric disorders.
Psychosocial factors may aggravate existing physical disorders or precipitate latent ones. For example, psychologic disorders (eg, anxiety) may lead to physical discomfort in more than half of elderly persons with gastrointestinal complaints. In the elderly, about half of the cases of gastrointestinal distress (eg, irritable colon, spastic colitis, gastritis, heartburn, nausea, diarrhea, constipation) have a psychogenic component. (see page 327)
Physical disorders may affect psychologic disorders. More than 25% of elderly persons have impaired hearing; in such persons, a sensory-deprivation phenomenon may cause psychotic symptoms (eg, delusions).
Coexisting physical and psychologic disorders may precipitate further physical or psychologic decline. A frail elderly person with depression or psychosis may be unable to correctly take drugs to treat physical ailments.