Prospective memory and medication adherence in schizophrenia : influencing factors and awareness of abilities
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Adherence to antipsychotic medication in schizophrenia has been shown to predict symptom exacerbations; however, adherence remains poor in this population. The concept of taking medication on a maintenance regime is an example of prospective memory (PM). The current investigation is comprised of three studies in which 59 outpatients diagnosed with schizophrenia completed a comprehensive assessment including measures of PM, executive functioning, comprehension of medication instructions, insight into the need for medication, and environmental variables supporting adherence. An objective measure of medication adherence was also collected during a one-month baseline period. In study 1, medication adherence was conceptualized as a PM task and variables for predicting adherence based on PM literature were examined. Of the hypothesized variables, the interactive effect of PM ability and comprehension of medication instructions was the only predictor of adherence to antipsychotic medication. Comprehension of medication instructions alone was the only predictor of adherence to total psychotropic medication regime. Study 2 investigated the role of executive functions in the awareness of PM deficits and use of compensatory strategies. Results indicated that patients with poorer executive skills were less reliable in their report of PM ability compared to performance on PM measures. However, both fair and poor executive functioning groups reported similar use of compensatory strategies. Lastly, the third study manipulated the specificity of retrieval context for a 5-day habitual PM task intended to mimic medication-taking. The aim of this investigation was to examine the effect of retrieval context specificity and executive functioning on task performance. Results demonstrated that patients categorized as fair executive functioning completed significantly more days of the habitual task than patients categorized as poor executive functioning. There was no difference in performance between patients receiving greater retrieval context specificity versus patients receiving a general context. However, there was a trend for individuals with fair executive functioning to benefit from greater retrieval context specificity, implying that a minimum level of executive skill may be necessary for individuals to recognize the risk of a restricted retrieval interval and/or mobilize additional resources for encoding. Clinical implications are discussed.