The number of older adults in the U.S. is increasing and, not surprisingly, older adults make up a significant percentage of inpatient consultations. The field of geriatric psychiatry is complex, but there are a few points to consider when treating the older patient.
Older patients are vulnerable to delirium and dementia, and it is important to have a careful longitudinal history to differentiate the two. Delirium would have a more acute onset.
Dementia & depression
Dementia can also be confused with depression. Depression is a serious problem in older adults and men over 75 commit suicide at a higher rate than any other age group. The prevalence of geriatric major depression in the general population is about 1-2%, but up to 15% of older adults may have depressive symptoms without meeting criteria for major depression. Relative to younger patients, older patients are more likely to minimize or deny depressed mood, become preoccupied with somatic symptoms, complain about memory, be divorced, widowed or separated, and have primary depression. Older adults are less likely to express guilt, seek help, or accept a psychological explanation for their illness.
Stroke precipitates major depression in 25-50% of patients.
Benzodiazepines
Anxiety is common amongst older adults and can often present as a complaint of insomnia. If benzodiazepines are prescribed, metabolic considerations are important as older adults have impaired oxidative metabolism. Conjugative metabolism is relatively spared, so lorazepam, oxazepam, and temazepam are better choices.
Pharmacological issues
A table of the effects of age-related changes on pharmacokinetics is here.
Distribution. Lean muscle mass and total body water decrease with age by about 10-15%. Thus, fat soluble medications have an increased volume of distribution, more accumulation, and a prolonged half-life. Many medications can remain in the system for a very extended time in older adults.
Hepatic. Hepatic blood flow can decrease by as much as 40% by age 65. Decreased blood flow in conjunction with decreased hepatic metabolic rates, can extend the half-life of many medications.