Although most guidelines about depression recommend continuation of medication for at least 8 months after symptom remission 50-80% of patients prescribed antidepressants either discontinue their medication prematurely or take it too inconsistently to derive any clinical benefit, which appears to increase the risk for relapse and recurrence. A large body of literature indicates that patients' beliefs and attitudes about medication predict medication adherence and treatment outcome. Despite this growing literature little is known about what underlies patients' beliefs about antidepressants. A U.S. study of 165 patients found that perceived necessity of antidepressants was associated with older age, more severe symptoms, longer anticipated duration of symptoms and the attribution of symptoms to a chemical imbalance. Perceived harmfulness was highest among patients who had not taken antidepressants before, who attributed their symptoms to random factors and who had an unclear understanding of depression. Neither belief - in the necessity or harmfulness of antidepressants - was significantly associated with sex, education, age at first depressive episode, presence of melancholia or anxiety, other mental-health problems or clinical settings.
Aikens, James E., Nease, Donald E. and Klinkman, Michael S. - Explaining patients' beliefs about the necessity and harmfulness of antidepressants Annals of Family Medicine 2008, 6: 23-29