Dementia--the failure of hippocampal plasticity and dreams. Is there a preventative role for melatonin?

Anatomic, chemical, physiologic, pathologic and clinical evidence suggests that senile dementia (Alzheimer's disease) is a dysfunction of the hippocampus. Failure of hippocampal plasticity could be secondary to loss of input from the medial septal nucleus and/or locus ceruleus or due to a functional abnormality. When compared to age-matched controls, demented patients have decreased hippocampal norepinephrine and serotonin, increased hippocampal monoamine oxidase, and decreased REM sleep. These observations could be explained by a melatonin deficiency. A chronic melatonin deficiency, with loss of dreams, could cause dementia.