CRY1 and major depressive disorder: TNF is also involved in some central nervous system pathologies such as Alzheimer.[24] At the same time, TNF has a role in influencing the circadian clock, mediated by the clock genes (Cry1 and Tef), with a direct action on these genes.[26] In particular, the abnormal expression of these genes, altered in cells stimulated by TNF, is associated with depression.