Transgenic mice given melatonin were protected from cognitive impairment in working memory, spatial reference learning/memory, and basic mnemonic function. Immunoreactive Aβ deposition was reduced in hippocampus and entorhinal cortex of melatonin treated transgenic mice. Melatonin decreased tumor necrosis factor-α in hippocampus and normalized cortical mRNA expression of antioxidant enzymes. This evidence concerns the gene TNF and Cognitive impairment.