A drink before dinner, even when it is the habit of a lifetime, may constitute drug misuse in elderly people and cause unanticipated and often undiagnosed problems, a new study suggests.

Moreover, the problem of inadvertent drug abuse by older people may be significantly more widespread than is generally believed, according to the study, published in the current issue of Psychology and Aging, a journal of the American Psychological Association.

In a six-month examination of 141 California residents (ages 65 to 74) psychologist Susan Folkman and colleagues found that almost half of the group (48 percent) misused drugs at least once. "Misuse" included failure to follow physician's instructions; unknowingly taking interacting drugs, including over-the-counter drugs with alcohol; and taking more than one drug in the same pharmacological classification -- thus accidentally overdosing.

Because the research sample comprised mainly affluent, well-educated people and earlier studies show that misuse is more common among the less affluent, Folkman wrote that "our finding that nearly one half of our subjects misused drugs may represent a tip-of-the-iceberg phenomenon."

Folkman wrote, "Health care professionals and elderly persons themselves {should} be made aware that seemingly innocent practices . . . can lead to unwanted psychological and somatic symptoms.