The study was conducted in 125 patients with probable AD who attended the outpatient clinic at the EuroEspes Biomedical Research Center from January 2004 to June 2011. We also recruited 60 elderly subjects who acted as healthy controls (HC). They consisted of neurologically and psychiatrically normal subjects visiting our center for clinical check-up or genetic and pharmacogenomic screening. All patients met the diagnosis of probable AD according to the National Institute of Neurological and Communicative Disorders and Stroke/the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) [43] and the DSM-IV [44] criteria. They underwent standard screening which involved physical and neuropsychiatric examination, laboratory tests (e.g., serum cholesterol, folic acid, vit B12, HIV, thyroid hormones), a neuropsychological battery, quantitative electroencephalogram (EEG), and neuroimaging tests using MRI or Computed Tomography (CT). The neuropsychological battery included the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) as a global rating scale that measures cognitive symptoms of the disease. The severity of dementia was assessed with the Mini-Mental State Examination (MMSE) [45] in all patients. In addition, the Global Deterioration Scale (GDS) was also assessed in most of
