Among the many effectors released by glial cells is brain-derived neurotrophic factor (BDNF), a neurotrophin characterized in AD by a biphasic pattern of expression with a significant rise in patients showing mild cognitive impairment (MCI), followed by a substantial drop in patients at more advanced stages of the disease, when neuritic degeneration and reduced spine density occur13. The gene discussed is BDNF; the disease is Cognitive impairment.