Introduction

We live in an aging society where the proportion of individuals over the age of 65 will continue to grow over the next few decades. Between 1946 and 1964, almost 76 million babies were born in the United States, a 53% increase over the preceding 19-year period. The oldest member of this baby boom generation will turn 65 in the year 2011, leading to an increase of about 22 million individuals over the age of 65 during the following decade.

The social upheaval that these baby boomers led in the 1960s and 1970s was accompanied by a dramatic increase in the use of illicit drugs. As they aged and matured in the late 1970s and early 1980s, however, many baby boomers settled down and entered mainstream society. Unfortunately, there is some suggestion that the use of drugs (i.e., alcohol, marijuana and other illicit drugs) during adolescence and early adulthood may predict continued use of the same substances in later life in a proportion of individuals (Kandel et al., 1986).

Prescription and OTC Drug Use

Elderly individuals use prescription drugs approximately three times as frequently as the general population, and the use of over-the-counter (OTC) medications by this group is even more extensive. The estimated annual expenditure on prescription drugs by the elderly in the United States is $15 billion, a fourfold greater per capita expenditure on medications compared to younger individuals, making the elderly the largest consumers of legal drugs in the United States (Schmucker, 1984).

The disproportionately greater exposure to medications, coupled with age-related physiologic changes in the pharmacokinetics (e.g., decreased elimination and increased accumulation) and pharmacodynamics (e.g., increased sensitivity to benzodiazepines) compared to younger individuals, increases the likelihood of medication-related adverse events.

Medication misuse is present when patients consciously or unconsciously consume medications in a manner that deviates from the recommended prescribed dose or instruction. Misuse may include overuse because of a belief that more is better, as well as underuse due to cost issues or as a method to avoid side effects. Abuse of prescribed or OTC drugs occurs when a patient continues to use the drug even when it is not required for the primary purpose for which it was recommended, or when the person takes it in greater than recommended amounts because of its psychotropic effects..

Illegal Drug Use

Cross-sectional data suggest that there is a low prevalence of illicit drug use among the current elderly. Less than 0.1% of the people in the Epidemiologic Catchment Area Study older than age 65 met DSM-III criteria for drug abuse/dependence in the previous month compared to a prevalence rate of 3.5% for the same period among 18- to 24-year-olds. (Regier et al., 1988). Longitudinal data from the National Survey on Drug Abuse suggest some interesting trends related to baby boomers.

In 1979, when baby boomers were aged 21 to 33 years, almost 14 million (27%) reported using any illicit drug in the past month. As baby boomers aged, the prevalence of that population using illicit drugs declined sharply until they reached their early thirties. At that time, illicit drug use leveled out, and has remained stable with about 5% of this cohort reporting use of an illicit drug in the previous year. This compares to a prevalence rate of approximately 3.8% among age-comparable individuals from the previous generation.

Alcohol Abuse in the Elderly

The incidence of heavy drinking-that is, 12 to 21 drinks per week-has been estimated to be between 3% and 9% among the elderly. Rates appear to be lower in older individuals compared to younger individuals (e.g., one-month prevalence of abuse and dependence was 6% in males ages 18 to 24 years versus 1.8% in older males) (Liberto et al., 1992). Some longitudinal studies suggest that alcohol consumption decreases with age, while others have reported stable or increased consumption. Cohort effects may account for some of these discrepancies. Alcohol abuse and dependence in the elderly are, however, likely to increase as baby boomers reach older age with heavier drinking habits than current cohorts of older adults (Reid and Anderson, 1997).

Diagnosing Substance Abuse

Compared to younger adults, substance abuse disorders present more often as medical or psychiatric conditions in older individuals. Therefore, criteria for substance abuse in younger individuals may not be appropriate for older populations. Both clinicians and researchers have most often relied on the DSM criteria, which were developed and validated in young or middle-aged samples, to diagnose substance abuse.

For example, the criterion of increased tolerance to the effects of the substance leading to increased consumption over time may not be valid in the elderly since age-associated changes in pharmacokinetics and physiology may alter their drug tolerance. Compared to a younger adult, a similar amount of alcohol consumed by an older individual may lead to increased intoxication due to decreased tolerance to alcohol. Problems of identification may be compounded since older adults often live alone, making detection of problems more difficult.

Minimizing OTC Misuse/Abuse

There are multiple reasons why an elderly person may misuse prescription or OTC medications. Since increased drug exposure is one factor associated with adverse or unwanted medication effects, every clinician should evaluate the medications being taken by an elderly patient. Polypharmacy should be avoided. In situations where communication is lacking and the patient may receive medications from multiple prescribers for similar conditions, polypharmacy is particularly likely to occur. One method of avoiding this is to recommend, if feasible, that elderly patients receive the majority of their prescriptions from a single pharmacy. The pharmacist could then help identify inappropriate methods of polypharmacy.

Deficits in cognition, vision, hearing and strength, all of which commonly occur with the aging process, could increase the likelihood of medication misuse. For example, an elderly person who is forgetful may overuse or underuse medications. Similarly, an elderly individual who has difficulty with reading the instructions on the vial or has difficulty hearing verbal instructions may take medications in a manner that deviates from the original intention. Finally, an elderly person with diminished strength, or one who has painful arthritis, may overuse (to minimize the number of painful attempts to obtain medication) or underuse (avoid taking medications) because of difficulties with the medication vial.

Treating Substance Abuse

For specific recommendations regarding the management of substance abuse, refer to the American Psychiatric Association's Practice Guideline for the Treatment of Patients with Substance Abuse. It is important to note, however, that while there is no evidence to suggest that the treatment modalities of substance abuse differ in younger adults compared to the elderly, little work has addressed issues that may be unique to the treatment of elderly substance abuse patients. For example, some research suggests that increased cognitive impairment is associated with poorer prognosis for recovery among people with alcohol dependence. Patients with cognitive impairments (e.g., problems with verbal abstraction) may not be able to take advantage of treatments that require higher order cognitive processing such as learning new problem-solving strategies (Gordon et al., 1988). Other problems with treatment may be encountered among patients who have dual diagnoses (e.g., substance abuse plus major depression); such patients usually need treatment for both the substance abuse and the psychiatric disorder.

Conclusion

Medication misuse and/or substance abuse is a complex problem among elderly populations. The disproportionately greater exposure to medications by the elderly, coupled with age-related physiological changes and problems related to medication compliance, places this population at great risk for adverse events. As life expectancy is extended, there may be increased morbidity associated with chronic diseases that may lead to increased use and abuse of prescription and OTC medications.

There is a general trend for a decrease in substance abuse over a person's life span, but increasing proportions of younger substance abusers are surviving into late life. These substance abusing survivors and individuals who develop drug problems later in life will cause an increase in the number of elderly drug abusers in our population.

There continues to be a perception that substance abuse and misuse in the elderly is not an important public health problem for society. Most of the emphasis has been placed on the study of younger populations without an appreciation of the unique problems presented by the elderly substance user. There is a need to develop a treatment infrastructure that is sensitive to problems of older substance users. This should include education of professionals as well as that of the public at large.