Estimating age-related changes in psychomotor function: influence of practice and of level of caloric intake in different genotypes

This article presents a discussion of some key considerations in the measur ement of age-related changes in psychomotor function of mice. We illustrate that "standard" measures of psychomotor performance, such as running speed on a rotorod task, are highly sensitive to practice effects. Examples are cited in which failure to assess practice effects can influence conclusions regarding the magnitude and rate of change in psychomotor capacity as a fu nction of age. A second set of examples is focused on estimating the effect of an experimental intervention, caloric restriction, on age-related chang es in psychomotor performance. These examples show that psychomotor perform ance at a given age may vary directly, and reversibly, with the level of ca loric intake. Independent of such reversible effects, the level of caloric intake can also modulate the rate of change in capacity as a function of ag e. It is concluded that reversible, short-term effects must be considered i n estimating the effect of an experimental intervention on the rate of age- associated change in psychomotor function. (C) 1999 Elsevier Science Inc. A ll rights reserved.