They forget; they can't afford the refill; or they can't abide the side effects. Maybe they're feeling pretty good and don't see a reason to continue. Or perhaps the opposite is true–they're feeling hopeless and can't see how any medication could possibly help.
The reasons for nonadherence to antidepressant medication are vast and complex, representing some of the most challenging conundrums psychiatrists in clinical practice have to face.
“Beyond the simple explanations, there are several complex issues that need to be considered,” said Dr. Carl B. Greiner in an interview.
Among them is the possibility that stopping the medication is a sign of “not liking the physician or general disagreement about the therapy.”
“The patient can exercise control by not following advice,” said Dr. Greiner, professor of psychiatry and vice chair of clinical affairs at the University of Nebraska's School of Medicine in Omaha.
Another possibility is that the patient might have suffered side effects from an antidepressant in the past and fears the same result.
“If the physician does not ask, the patient may simply not even fill the prescription,” he said. “The point is that the physician needs to think broadly and talk with the patient to determine what brought them to [never start] or to stop the medication. The patient might not declare the reason, but the offer of a discussion is a good start.”
The literature offers perspective on issues underlying nonadherence, but no clear guidance on how to improve compliance.
Findings from studies show that 50% to 75% of patients quit taking their antidepressants within 6 months of receiving a prescription.
In one large observational cohort study, patients treated by psychiatrists fared somewhat better in regard to adherence than did those treated by primary care physicians or other specialists. Nevertheless, 13% of psychiatrists' patients were immediately noncompliant (never refilling an antidepressant prescription), and 49% failed to complete 6 months of therapy even after refilling a prescription at least once (J. Clin. Psychiatry 2007;68:867-73).
Many studies have examined risk factors for discontinuing antidepressants early in the course of therapy, quite consistently pointing to higher nonadherence rates in the very young and very old, patients with comorbid psychiatric or physical conditions, substance users, lower income and less educated patients, and those who are not concurrently undergoing psychotherapy.
Side effects, especially sexual side effects, emerge as significant barriers to continued therapy.
But so, increasingly, is cost.
“The patient might cut back on usage to extend the prescription,” Dr. Greiner said. “A more dire concern [for the patient] is whether to take the medication or buy basics such as food.”
Even in Canada, where medication costs are not an important factor, noncompliance rates are considerable.
A telephone survey of 5,323 adults conducted in the province of Alberta found noncompliance rates of between 42% and 47% in patients prescribed between one and three antidepressants (Can. J. Psychiatry 2006;51:719-22).
The chief reason given for failing to comply, offered by nearly 65% of patients prescribed one medication in the study, was forgetfulness, a possible symptom of major depression.
Other factors directly related to depressive symptoms also might interfere with compliance.
Deep in the clutches of a depressive episode, “Some individuals feel, 'Why bother? It won't help, anyway,'” said Dr. Ellen Haller, professor of clinical psychiatry and director of the general adult residency training program at the University of California San Francisco's department of psychiatry.
“That sense of helplessness and hopelessness, which is a symptom of the condition, can also get in the way of people accepting help,” she said.
Social stigma commonly prompts patients to quit taking their medication, when family or friends suggest that continued use will lead to being “addicted” to antidepressants, she added.
“When someone stops taking their antihypertensive, and then their hypertension returns, no one says, 'You must be addicted to that antihypertensive.' Yet, if the identical situation occurs with depression, individuals often do develop the belief that they must be addicted, or people close to them hold that belief.
“So, education, education, education!” Dr. Haller said.
Dr. Greiner said stigma also is at the root of vulnerability conferred by the use of psychiatric medications in some populations, since it might be interpreted as “proof” that someone is “crazy.”
“In prison populations, some avoid taking medication because it might indicate vulnerability to fellow inmates. In some families, taking medication would be an indicator that the patient does not need to be regarded in conversations,” he said.
Even patients suffering profound symptoms might convince themselves that if they are not taking medication, their symptoms do not represent psychiatric illness.