The importance of homeostasis of neural tissue to neuron functioning, the synaptic plasticity of the hippocampus, and laboratory animals' behavior was demonstrated by the authors earlier. A range of experimental data evidences that cholinergic neurotransmission, ionotropic and metabotropic receptors, excessive tau phosphorylation, alterations in amyloid-B biochemistry, oxidative reactions, and other features of neurodegenerative processes depend on the precise regulation of cerebral cholesterol metabolism. Such results suggest that disturbances in cholesterol homeostasis are the common primary cause of the sporadic and familial forms of Alzheimer's disease, Down syndrome, Niemann-Pick disease type C, and explain the similarity of neurodegenerative signs in different degenerative diseases of the nervous system. The present work was introduced at an annual conference of American Society for Neuroscience, and is available as a scientific report at www.neurobiologyoflipids org/content/3/7/.