Study Homes In on Patients' Beliefs Affecting Antidepressant Adherence

Patients' beliefs about antidepressant drugs are a key factor driving adherence to therapy. According to a recent study, beliefs about efficacy and adverse effects, along with demographic attributes, are among the factors affecting antidepressant adherence.

At least half of patients receiving antidepressants for their depression fail to adhere to treatment recommendations, and studies to date have not been terribly helpful in pointing to solutions to this problem. Researchers from the University of Michigan have been assessing patients' beliefs about antidepressants and the factors underlying those beliefs. Findings from their most recent study were published earlier this year in Annals of Family Medicine.¹

James Aikens, PhD, the study's lead author and assistant professor of psychiatry at the University of Michigan Medical School, pointed out that although depression treatment guidelines recommend continuing antidepressant medication for at least 8 months after symptom remission and regimen stabilization, 50% to 83% of patients either discontinue their medication early or take it too inconsistently to derive clinical benefit, thereby increasing their risk for relapse and recurrence.

Unfortunately, most studies evaluating ways to promote antidepressant adherence have yielded disappointing findings, Aikens said, "so new strategies are called for."

Medication beliefs often are the hidden determinant in treatment outcome, he said, pointing to an earlier University of Michigan study demonstrating that patients' adherence to maintenance antidepressant therapy varied according to their beliefs about the medications.² Aikens and colleagues' current study involved 165 patients with unipolar nonpsychotic major depression who were recruited from primary care and psychiatric clinics and who were participating in the baseline phase of the STAR*D (Sequenced Treatment Alternatives to Relieve Depression) trial funded by NIMH. Before patients started taking antidepressants, they were assessed for psychiatric status, psychiatric and medical history, demographics, medication beliefs, and illness perceptions. The Beliefs About Medicines Questionnaire (BMQ), which assesses medication-specific and general beliefs, was used to measure the patients' perceived need for the medication and their concerns (perceived harmfulness) about the medication.

The data were collected before the initiation of the current treatment episode, making them unique, according to Aikens. In other studies of adherence issues, he said, most of the data were collected on patients who were already taking the medication.

Findings in the current study suggest that depressed patients' beliefs about antidepressants are associated with a rational and limited set of variables. "We found that some patients were deeply skeptical about starting an antidepressant, particularly those who were antidepressant-naive, those who tended to look at their depressive symptoms as mild and transient, and those who had only a vague idea about what they thought was causing their depression," Aikens told Psychiatric Times.

Skepticism, according to Aikens, is actually somewhat complicated and can be related to the perceived necessity and/or the perceived harmfulness of taking medications. While a biological psychiatrist has a detailed biological model of depression and a psychotherapist may have a highly detailed cognitive model of depression, Aikens said, "these patients have no particular model... it is not something they have thought much about or have any conclusions about... These may be people who are at high risk for nonadherence."

Aikens and his team found that perceived necessity was associated with patients who were older, who had more severe depressive symptoms, who had an expectation that the symptoms would last a long time, and who had a belief in the biochemical model. Perceived harmfulness was highest among those who had never taken an antidepressant before, who attributed their symptoms to bad luck or chance, and who had a vague or poorly differentiated personal theory of depression. Neither belief was significantly associated with sex of patient, educational level, age at first depressive episode, clinical setting, medical comorbidity, or any depression subtypes (anxious, melancholic, or atypical).