Fig. 1

The schematic diagram of pineal gland dysfunction in AD, immune-pineal axis, and the role of melatonin in neurogenesis. a Pineal calcification and reduced pineal volume causes pineal dysfunction, which are commonly observed in AD brain. The pineal dysfunction leads to the reduction of melatonin level, subsequently results in sleep deficit. b Immune cells could regulate NF-κB activation and promote the production of melatonin in pinealocytes through CREB-AANAT signaling. c The decreased melatonin level leads to the impairment of neurogenesis in AD, because reduced melatonin level contributes the reduction of BDNF and GDNF expression, which are known as boosters in neurogenesis