Because the results came from self-reported data, the actual numbers may be higher, say co-authors Thomas J. Moore, a senior scientist, drug safety and policy, at the Institute for Safe Medication Practices and lecturer at Milken Institute School of Public Health of The George Washington University, and Dr. Donald R. Mattison, chief medical officer at Risk Sciences International in Ottawa.
Importantly, the study found that older adults, between the ages of 60 and 85, are now the highest users of psychiatric medicines: More than a quarter of people between the ages of 60 and 85 reported use, compared with just 9% of those between the ages of 18 and 39 and nearly 18% of adults between the ages of 40 and 59.
"It used to be middle-aged adults were the highest users of these drugs; now it's older adults," said Dr. Eric Lenze, a professor of psychiatry at the Washington University School of Medicine, who is not affiliated with the study. He said this finding is "new and fairly eye-opening," especially considering that the oldest adults may risk falls and cognitive impairment from taking these drugs.
Additionally, Moore and Mattison say the majority of adults in the survey who reported taking psychiatric medications have been using them for a long time.
"My concern about the extensive long-term use is that eight of the 10 most widely used drugs either have warnings about withdrawal symptoms, are DEA Schedule IV or both," Moore said. "Both patients and physicians need to periodically re-evaluate the continued need for psychiatric drugs." The Drug Enforcement Administration's Schedule IV rating means a drug has a low potential for abuse and dependence.
He added that patients need to understand that stopping a psychiatric drug may seem to make the problem come back. But withdrawal or rebound symptoms may not occur when doctors carefully help patients taper their dose, Moore explained.
To understand adult use of psychiatric drugs and explore possible differences along lines of sex, age and ethnicity, Moore and Mattison turned to the 2013 Medical Expenditure Panel Survey
, which collects data from individuals, families and their medical providers and employers across the United States. The survey has been conducted annually since 1996 by the US Department of Health and Human Services.
Specifically, the co-authors focused on three classes of psychiatric drugs: antidepressants; anxiolytics, sedatives and hypnotics, used to treat anxiety and insomnia; and antipsychotics, mostly prescribed to patients who have mania from bipolar disorder or psychosis arising from schizophrenia.
The researchers found that nearly 17% of adults reported filling one or more prescriptions for psychiatric drugs in 2013. Among them, more than eight of 10 reported long-term use: filling a prescription three or more times or beginning a prescription in 2011.
Overall, 12% of adults reported antidepressant use; 8.3% reported taking anti-anxiety meds, sedatives and hypnotics; and 1.6% reported filling a prescription for antipsychotics.
Specifically, the top 10 psychiatric drugs reported in the new study were sertraline hydrochloride (Zoloft, an antidepressant); citalopram hydrobromide (Celexa, an antidepressant); alprazolam (Xanax, an anti-anxiety drug); zolpidem tartrate (Ambien, a hypnotic); fluoxetine hydrochloride (Prozac, an antidepressant); trazodone hydrochloride (Desyrel, an antidepressant); clonazepam (Klonopin, an anti-anxiety drug); lorazepam (Ativan, an anti-anxiety drug); escitalopram oxalate (Lexapro, an antidepressant); and duloxetine hydrochloride (Cymbalta, an antidepressant).
Drug use is unevenly distributed across the population, according to the study: 20.8% of white adults reported use of psychiatric drugs, compared with 8.7% of Hispanic adults, 9.7% of black adults and 4.8% of Asian adults.
The use of psychiatric drugs also appeared to increase with age, and women were more likely than men to report using psychiatric drugs.
"One out of five women reported taking a psychiatric drug during the one-year period," Moore said, adding that the data do not indicate the reasons for differences in use between groups.
Differences in rates could result from a combination of differences in socioeconomic status, education and the means to get the resources (for example, knowing how to enroll in Medicare), according to Dr. Scott Krakower, an assistant professor of psychiatry at Zucker Hillside Hospital in New Hyde Park, New York. Cultural differences may also play a part.
"We might not be reaching out to certain parts of the population," said Krakower, who was not involved in the study.
Men might generally be more dismissive of symptoms than women and so do not seek treatment, Krakower ventured.
Another factor influencing different rates of use may be the prescribers themselves. Since psychiatrists are an underrepresented specialty in certain areas of the country, primary care doctors, ob/gyns and other doctors are increasingly prescribing drugs for mental illness, Krakower explained. Yet many doctors may not be familiar with all the available drugs.
As a result, certain drugs may be prescribed more often than others due to each individual doctor's comfort level. For instance, "general practitioners are usually more leery of antipsychotics," he observed.
"You may have patients with untreated mood disorders who are really taking Ambien to solve sleep when they really should probably be on mood stabilizers," Krakower said. "Patients say, 'I'm having trouble sleeping. I'm irritable and awake,' and the doctor treats the symptom rather than treating the disease."