Participants

A total of 161 patients diagnosed with SIVD aged from 54 to 75 were recruited from the Department of Neurology in The First Affiliated Hospital of Anhui Medical University and Tongling Forth People's Hospital from February 2013 to August 2014. Fifty‐four healthy participants (25 men, 29 women; mean age: 65 ± 9 years) were recruited from the Health Examination Center of Tongling Forth People's Hospital as controls. All control participants were functioning normally and had no sign of cognitive decline, without prior or present neurological or psychiatric disorders.

Each enrolled subject underwent a standardized personal interview for acquirement of data on basic information, lifestyle, clinical diagnosis, and medical history, and permitted an extensive clinical assessment and the collection of blood samples for the determination of serum biomarkers. Written informed consent was given by all participants. Health status of controls and patients was recorded by assessing vascular risk factors including hypertension, diabetes, history of cardiovascular disease and stroke, and long‐term past or present smoking (≥10 years) (Table 1). Hypertension was defined if the subject presented a systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg. Diabetes mellitus was defined if the subject presented a fasting blood glucose ≥126 mg/dL (Bensenor et al. 2010).

General characteristics of study population

Data are presented as means ± SD or numbers with percentages in parentheses.

SIVD, subcortical ischemic vascular disease; SIVDND, subcortical ischemic vascular disease no dementia; SVMCI, small vascular mild cognitive impairment; VD, vascular dementia.

Exclusion criteria for controls and all patients were: suspicion of Alzheimer's disease, diagnosis with a chronic or degenerative diseases, known thyroid disease, history of brain injury or alcohol abuse, treatment with medication which could influence thyroid or brain function within 4 weeks before the testing, inability to give an informed consent, and unclassifiable cognitive status because of inability to complete the psychological test due to aphasia, intelligence disturbance, depression, and psychiatric disorders. Specifically, SIVD diagnosis were determined in accordance with internationally accepted diagnostic criteria (Roman et al. 2002), and AD participants were excluded, based on the diagnosis at a multidisciplinary case conference using the National Institute of Neurological and Communicative Disorders and Stroke (NIHCDS) and the Alzheimer's Disease and Related Disorders Association (ADRDA) diagnostic criteria.