The cognitive footprint of medication: A review of cognitive assessments in clinical trials.

Abstract

Polypharmacy is common, and many medications have cognitive side effects. Such effects can be transient and subside when the drug in question is discontinued or can be long-lasting with effects present for years afterwards. Although formal assessment of cognition is feasible and often undertaken in neuropsychiatric trials, these effects are usually neglected in the evaluation of any non-neuropsychiatric health intervention. Medication effects can be assessed within a cognitive footprint framework, to account for the magnitude and the duration of cognitive side effects, with some likely to have a greater and more lasting effect than others. Adverse event reporting suggests that many medications may be indirectly associated with cognitive effects, for example due to headaches, somnolence and 'dizziness'; however, inferring causation from adverse event reporting can be problematic. In order to better understand the impact of investigational drug and concomitant medications effect on cognition, it would be essential to ensure cognition is prioritized in drug development evaluation. It is suggested that simple instruments that can be easily incorporated into existing trial designs are used to assess the cognitive footprint of medication. We present an overview of existing measures of cognition that can be integrated into drug trials in order to provide a cognitive footprint. Like quality of life testing, such tests should be administered as a standard throughout the key assessment stages of the design of the trial to ensure that any effects on this equally important outcome are also documented. Furthermore, employing routine cognition testing may also enable researchers to identify unanticipated beneficial and non-beneficial effects on cognition. Provision of such a cognitive footprint profile of drugs may provide the necessary evidence to enable decision-makers to make informed decisions on risk-benefit analysis that can subsequently make trade-offs between different drug regimens.