Subjects

All the participants in the present study have been described in detail in our previous research (Song et al., 2013; He et al., 2014; Liu et al., 2014). The participants were recruited by advertisement, and they and various aspects of the study were supported by medical personnel from a neuropsychological research facility at Xuanwu Hospital, Beijing, China. None of the participants had any contraindications for MRI scanning. Written consent forms were obtained from all subjects or their legal guardians (usually a family member). The study was approved by the ethics committee of Xuanwu Hospital. Following the criteria of our previous studies, 18 patients with MCI, 17 patients with mAD, 18 patients with sAD, and 21 healthy controls were all included in the present study. The AD patients were diagnosed using standard operationalized criteria DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition); NINCDS-ADRDA (American Psychiatric Association, 1994 and National Institute of Neurological and Communicative Disorders and Stroke—AD and Related Disorders Association); (McKhann et al., 1984). The severity of dementia was assessed using the clinical dementia rating (CDR) scale (Morris, 1993). AD patients with a CDR score of 1 were diagnosed as having mAD and those with a CDR score of 2 or 3 were diagnosed as having sAD. MCI was diagnosed using standard criteria (Petersen et al., 1999, 2001; Choo et al., 2007), which included subjective memory loss with objective evidence of memory impairment in the context of normal or near-normal performance on other domains of cognitive functioning; minimal impairment of activities of daily living; and a CDR score of 0.5. The healthy controls had a CDR score of zero. None of the subjects had head movements of >3 mm translation or >3° angular rotation in any axis during scanning. Demographic and psychological characteristics of the samples are summarized in Table ​Table11.

Demographics and clinical characteristics.

Note: A Pearson chi-squared test was used for gender comparison. One-way ANOVAs with Bonferroni-corrected post hoc t-tests were used for age, education and MMSE comparisons. MMSE, mini-mental state examination; CDR, clinical dementia rating.