Obesity is a serious global health problem and is associated with a variety of chronic diseases. Increasing evidence suggests that obesity increases the risk of Alzheimer's disease. Several studies have shown that a Mediterranean diet is effective in reducing weight and epidemiological data suggest that such a diet is associated with lower risk of neurodegenerative disorders, including Alzheimer's disease. Therefore, we examined the relationship between obesity and neurodegeneration and the possible effects of Mediterranean diet on both in adult obese rats. Obese rats showed significant dyslipidaemia, insulin resistance, down-regulation of adiponectin mRNA expression in adipose tissue, up-regulation of brain amyloid precursor protein, apolipoprotein E and caspase-3 mRNA expression and a marked increase in brain oxidative stress. Treatment with Mediterranean diet induced significant weight loss and improvement in these various markers. The present study suggests that Mediterranean diet is a viable nutritional intervention in obesity and, more importantly, in the prevention and treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]