CREB1 and Alzheimer disease: Also, in AD patients, p-CREB expression in peripheral blood mononuclear cells (PBMCs) correlates with expression in the brain and alters CREB signaling in the brain, thus exacerbating cognitive decline in AD.[31] Disturbances in CREB phosphorylation and transcriptional mechanisms interacting with CREB play a key role in synaptic dysfunction and memory loss.[32]