Contraindicated medication use among patients in a memory disorders clinic

Inappropriate or contraindicated use of medications in elderly patients is common and associated with poor outcomes. An important risk factor for adverse drug events is the increased sensitivity to drug effects on the central nervous system (CNS). There is a high rate of use of CNS-active drugs in patients with cognitive impairment, despite the fact that these medications may worsen cognition and be a possible "reversible" cause of memory loss.

The goals of this study were to establish the prevalence of these contraindicated medications in a population of elderly patients referred to a memory disorders clinic for evaluation and to determine if those individuals receiving contraindicated medications had specific characteristics. This included determining how many patients were concurrently being prescribed a cholinesterase inhibitor.

The review included new patients consecutively evaluated for cognitive complaints in a memory disorders clinic between June 2003 and August 2004. Each patient underwent a comprehensive evaluation by a multi-disciplinary team during a 3-hour clinic appointment. A thorough history of cognitive deficits and associated symptoms was obtained by the physician, who also performed a comprehensive neurologic examination. All patients underwent neuropsychologic testing with an extensive cognitive battery. In addition, patients' electronic medical records were reviewed to determine a list of prescribed and over-the-counter medications at the time of the initial referral. Contraindicated medications were identified using the updated Beers criteria of medications that should be avoided in older patients with cognitive impairment or that have high CNS adverse effects.

A total of 100 patients (91 men, 9 women; mean [SD] age, 75.8 [9.7] years; 73% white) were included in the study. Eighty-six patients were determined at the time of evaluation to have some kind of cognitive impairment. They were mildly impaired, with a mean (SD) Mini-Mental State Examination score of 22.9 (5.1), based on a scale of 0 to 30. Twenty-two patients were taking > or =1 contraindicated medication that could potentially affect their cognition; the most frequently prescribed were benzodiazepines, oxybutynin, amitriptyline, fluoxetine, and diphenhydramine. Twenty-eight of the 100 patients were being treated with a cholinesterase inhibitor at the time of their evaluation; of these, 4 (14%) were also taking > or =1 medication with anticholinergic properties.

Despite research evidence and recommendations to avoid these CNS-active medications because of their adverse effects, they continue to be prescribed in elderly patients with cognitive impairments. Further research is needed to determine strategies that will help reduce their administration in this population.