Impact of symptom resolution on medication adherence in first episode psychosis.

Adequate adherence to medication confers benefits on patients with psychotic illness, but is difficult to achieve. Efficacy of medication influences adherence in patients in advanced phases of illness and may have a similar influence on patients with a first episode of psychosis (FEP). We assessed medication adherence and efficacy in 216 FEP patients at program entry and at 3 and 6 months later. "Efficacy" was evaluated as the ability of medication to reduce positive or negative symptoms to below established thresholds for clinical remission at each evaluation. Adherence was defined as adequate (>75%) or not. Resolution of negative symptoms by month 3 of treatment was associated with inadequate adherence at months 3 and 6. In contrast, rapid resolution of positive symptoms showed no relationship to adherence. In a multivariate analysis taking into account other determinants of adherence in FEP, the role of early negative symptom remission was confirmed, and we found that a 3-month sustained remission of positive symptoms was associated with adequate adherence. Medication efficacy may promote adherence if it produces sustained remission of positive symptoms. However, many patients who benefit from medication, particularly those with rapid improvement of negative symptoms, fail to adhere to the treatment.