To our knowledge, this is the first report that the effects of peripubertal GnRHa-treatment to reduce long-term spatial reference memory will persists following GnRHa withdrawal and suggests that these effects are permanent. Studies on the use of GnRHa in adult humans (Freedland et al., 2009, Green et al., 2000) have reported impaired cognition and memory loss, which were ascribed to the associated loss of estrogen and/or testosterone. Beer et al. (2006) reported that long-term memory was reduced, in terms of compromised immediate and delayed verbal memory, in men with prostate cancer and androgen deprivation (primarily GnRHa-mediated) compared to untreated healthy Controls. Another study, on elderly men with prostate cancer and GnRHa-mediated androgen deprivation (Salminen et al., 2004), reported that a decline in testosterone was associated with slower visuo-motor speed, slower reaction times relating to working memory, reduced recognition speed and delayed recall of letters, but improved object recall. These observations support the conclusion of the current ovine study that spatial working memory is reduced by the loss of testosterone, and that restoration of testosterone, either via replacement therapy (Hough et al., 2016) or gonadal development following GnRHa-withdrawal, results in normal function. However, deficits in long-term spatial reference memory did not improve with exposure to endogenous testosterone and are likely permanently altered by the changes in GnRH signaling that occurred during the peripubertal period. In so doing, it identifies the peripubertal period as a critical window of development with regard to spatial memory, in which GnRH signaling is involved. The observation that peripubertal GnRHa-treatment is associated with permanent changes in brain development raises particular concerns about the cognitive changes associated with the prolonged use of GnRHa-treatment in children and adolescents.