Antidepressant drugs represent the mainstay of treatment for depression; however, nonadherence is a major problem. Attitudes are predictors of long-term adherence and drive medication use. The Attitudes Toward Medication-Depression (ATM-D) Inventory was developed and tested with 131 patients in primary care settings who reported a diagnosis of depression. Content validity was assessed by experts with a 94.4% agreement on item relevancy. Exploratory factor analysis showed three factors (course of medication treatment, identity, and control) that accounted for 57% of the total variance in the final 17-item scale. The instrument demonstrated good internal consistency reliability (α = .76-.84) and test-retest reliability (α = .74-.83). Results support the construct validity and reliability of the instrument and revealed unique insights into patients' cognitive representations of their antidepressants. This study supported that patients have cognitive representations related to depression and antidepressants that go beyond simple concerns about the effects of the medication.
Keywords: adherence; antidepressants; cognitive representations; depression; instrument development.