The miRNA 107 gene is increasingly appreciated to serve key functions in humans. The miRNA regulate gene expression involved in cell division, metabolism, stress response, and angiogenesis in vertebrate species. But the relationship and diagnosis capability of miRNA 107 and BACE1 mRNA gene expression in plasma and cerebrospinal fluid (CSF) of amnestic mild cognitive impairment (aMCI) and normal control is still a mystery.

The Real-Time PCR was the main method in the research.

Inclusion Criteria:

• Probable Alzheimer's disease (AD) was diagnosed according to the Diagnostic and Statistical Manual for Mental Disorders 4th edition (DSM-IV) criteria and the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorder's Association (NINCDS/ADRDA) criteria.
• AMCI was diagnosed based on the following criteria (Petersen et al., 2001): 1) memory complaint, preferably corroborated by a spouse or relative, 2) objective memory impairment, 3) normal general cognitive function, 4) intact activities of daily living, and 5) absence of dementia. We have amended the aMCI diagnostic criteria of the Petersen Mini-Mental State Examination (MMSE) cut-off score in order to be consistent with the low level of education in elderly Chinese people. Research (mingyuan Zhang et al, 1988) found that with the Chinese version of MMSE, AD subjects who had not been educated (NO ED) exhibited MMSE scores of <18, those with elementary school education exhibited MMSE scores of <21, and those with higher than middle school education exhibited MMSE scores of <25. In the present study, the aMCI analysis was carried out on NO ED subjects with MMSE cut-off scores of over 18, elementary school educated subjects with MMSE cut-off scores of over 21, and higher than middle school educated subject with MMSE cut-off scores of over 25.
• The cognitively-normal elderly formed the normal control (NC) group, was independently-functioning community dwellers with no neurological or psychiatric conditions.

Exclusion Criteria:

• All participants underwent a screening process that included a review of their medical history, physical and neurological examinations, laboratory tests, and MRI analysis. The clinical assessment of mild cognitive impairment or dementia included neuropsychological tests, as well as behavioral and psychiatric interviews conducted by the attending psychiatrist. AD patients recorded scores of < 4 on the Hachinski Ischemia Scale and showed no history of significant systemic or psychiatric conditions, or traumatic brain injuries that could compromise brain function.

the subjects were collected from Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine (Alzheimer's Disease and Related Disorders Center, ADRDC) and the of Shanghai Changning district, Huangpu district and Putuo district.