The impact of medical illness on executive function.

Executive function can be defined as one's ability to plan, initiate, sequence, monitor, and inhibit complex goal-directed behaviors. Although executive impairment is generally associated with dementia, recent studies have suggested that patients with chronic diseases, such as hypertension, chronic obstructive pulmonary disease, and diabetes, may also have executive deficits independent of psychiatric comorbidities. Because executive function is associated with functional outcomes, medication compliance, and the capacity to give informed consent, it is important that it be assessed. However, it is the authors' impression that executive function is not adequately assessed in medical settings, despite the availability of reliable measures. This article reviews the impact of medical illness on executive function and discusses practical diagnostic instruments and treatment strategies. The changes in functional status associated with executive impairment as well as pathophysiology and treatment strategies are also discussed.