The past psychiatric history includes a chronological summary of all past episodes of mental illness, including substance use disorders, and treatment. The summary includes prior hospitalizations; suicide attempts, aborted suicide attempts, or other self-destructive behavior; psychiatric syndromes not formally diagnosed at the time; previously established diagnoses; treatments offered; and responses to and satisfaction with treatment. With respect to psychotherapy, it is important to ascertain the type (e.g., psychodynamic, cognitive, behavioral, supportive), format (e.g., group, individual, couple), frequency, duration, patient's perception of the alliance, and adherence. With respect to medications, the dose, efficacy, side effects, treatment duration, and adherence are important to ascertain while understanding that reporting errors are more likely to occur when treatment involved more than one medication (46). With respect to other somatic therapies such as electroconvulsive therapy, information on the number of treatment sessions, treatment course duration, technical parameters, efficacy, and side effects is similarly useful to obtain. When past medical records are available and readily accessible, it is important that they be consulted for ancillary information.

The chronological summary also delineates the most recent periods of stability as well as episodes when the patient was functionally impaired or seriously distressed by mental or behavioral symptoms, even if no formal treatment occurred. Such episodes frequently can be identified by asking the patient about the past use of psychotropic medications prescribed by other clinicians and otherwise unexplained episodes of social or occupational disability.