title: 'Two-level' measurements of processing speed as cognitive markers in the differential diagnosis of DSM-5 mild neurocognitive disorders (NCD).
abstract: Processing speed is an updated diagnostic factor for neurocognitive disorders (NCD) in DSM-5. This study investigated the characteristics of processing speed and their diagnostic values in NCD patients. A flanker test was conducted in 31 adults with NCD due to vascular disease (NCD-vascular), 36 patients with NCD due to Alzheimer's disease (NCD-AD), and 137 healthy controls. The processing speed was evaluated using two measurements: mean reaction time (RT) and intra-individual variability of RT. Mean RT represents the global processing speed. Intra-individual variability of RT is the short-term fluctuation of RT and consists of two indices, which are intra-individual coefficient of variation of reaction time (ICV-RT) and intra-individual standard deviations (iSD). We observed elevated ICV-RT and iSD in NCD-AD and NCD-vascular patients. Additionally, there was a slowed RT in NCD-AD patients. The intra-individual variability of RT had a moderate power to differentiate NCD subgroups. The mean RT was able to discriminate the NCD-AD from NCD-vascular patients. Our findings highlight the clinical utility of the combined 'two-level' measurements of processing speed to distinguish between individuals with different cognitive status. Furthermore, the 'two-level' features of processing speed embedded in the psychometric property may also reflect the diverse aetiology underlying certain 'disease-specific' neurocognitive disorders.
authors.affiliation: Guangzhou Brain Hospital, The Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou, China. hannabrainscience@gmail.com.|Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong SAR, China. hannabrainscience@gmail.com.
authors.forename: Hanna
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Sandra S M
authors.initials: SSM
authors.lastname: Chan
authors.affiliation: Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Linda C W
authors.initials: LCW
authors.lastname: Lam
mesh_terms: D000368:Aged; D015415:Biomarkers; D003071:Cognition; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000523:psychology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D012372:ROC Curve; D011930:Reaction Time; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers