Relating hippocampal neurogenesis to behavior: the dangers of ignoring confounding variables.

Levels of hippocampal neurogenesis are associated with certain learning and memory tasks and with depression-like behavior in rodents. However, simply correlating neurogenesis with behavior can lead to spurious results unless other relevant factors such as age, disease status, or experimental condition are taken into account. A reanalysis of recently published data showed that after adjusting for the age of the rats, there was no significant relationship between the number of doublecortin-positive cells and working memory.