The effects of high fat diets and environmental influences on cognitive performance in rats

As part of a continuing investigation of the relationship between dietary f actors and cognitive function, the present study examined the combined effe cts of environmental influences and high-fat diets on learning and memory. Following 3 months of dietary (20% by weight fat diets, composed primarily of either beef tallow or soybean oil versus standard laboratory chow) and e nvironmental treatments (standard, enriched or impoverished), subjects were tested on a variable interval delayed alternation (VIDA) task which measur es learning and memory functions that differentially involve specific brain regions. The results confirmed the negative effects of high fat diets, rel ative to chow, on all aspects of VIDA performance and showed that environme ntal enrichment overcame deficits associated with dietary fat. Housing rats fed high-fat diets in an impoverished environment did not further exacerba te cognitive deficits observed in such rats living under standard condition s. By comparison, chow-fed rats exhibited no benefit associated with the en riched environment on any aspect of task performance, and only a transitory learning impairment when housed in an impoverished environment. The result s show that high fat diets and environmental conditions influence cognitive function and that these two factors interact with one another to produce d ifferent profiles of benefits and impairments. (C) 1999 Elsevier Science B. V. All rights reserved.