Enduring Behavioural Effects in Rats Treated with Caffeine During Adolescence

Abstract

Children and adolescents are regular consumers of caffeine, and their consumption is increasing. Caffeine has been shown to affect the later behaviour of rats and mice when exposed to the drug daily before birth and during the lactational period of development. However, to date, little research has investigated the effects caffeine consumption may have on adolescent brain development, and the behavioural consequences of this. The present study, therefore, investigated the effects of repeated caffeine exposure on adolescent rats on behavioural measures of anxiety. During middle and later adulthood, the rats’ activity and emotional reactivity were assessed by means of frequencies of rearing, ambulation, immobility, defaecation and urination recorded in an open field, as well as their occupancy of corners and centre squares of the field, and their partial emergence and latencies to fully emerge from a small darkened chamber into a brightly lit arena. The results showed that those rats treated with caffeine were probably more emotionally reactive than untreated controls, as suggested by more immobility, defaecation and urination. There were also effects on rearing and ambulation that might have arisen from increased impulsivity. Overall, the results suggest that exposure to caffeine during adolescence produces some small but significant increases in emotionality in adulthood. This study may have clinical implications, as it is possible that people exposed to caffeine as adolescents, may show increased anxiety later in life.