ABSTRACT
Objective To investigate the cognitive impairment and time-on-task characteristics of combined type(C type) and predominantly inattentive type (Ⅰ type) of children with attention deficit hyperactivity disorder(ADHD).Methods 24 cases with C type ADHD,20 cases with Ⅰ type ADHD and 24 normal children were completed 2 Block period of continuous performance test task,with conducting a comparative analysis of the behavior results of three groups and block1 and block2.Results 1.three groups comparison:hit numbers of C type (64.37 ±5.29) and Ⅰ type (63.55 ±5.28) were lower than that of the normal control group(67.04 ±2.03) ; reaction time of Ⅰ type (540.33 ± 90.33) ms was longer than that of the normal control group (470.56 ± 95.39)ms; intra-individual variability(ⅡⅤ) of C type (174.24 ± 56.3)ms and Ⅰ type (201.12 ± 50.79)ms were higher than that of the normal control group(144.72 ± 37.17) ms.Commission errors of other figures after 1 of C type was higher than that of Ⅰ type; reaction time of commission errors of Ⅰ type[(701.34 ±311.54) ms] was longer than that of C type((512.57 ± 279.22)ms),and all the differences were statistically significant (P ＜ 0.05).2.Timeon-task comparison:hit numbers,omission errors and ⅡⅤ had the significantly main effect of the type of subjects (P ＜ 0.05) ; hit numbers,omission errors,reaction time and ⅡⅤ had the significantly main effect of time-on-task (P＜0.01) ; Block2 the reaction time of C type and Ⅰ type((501.82 ± 112.47)ms,559.33 ± 90.73)ms) were significantly longer than that of Block1 ((473.19 ± 106.43) ms,(523.45 ± 99.86) ms) (P ＜ 0.05),while no significant difference (P＞0.05) in the normal control group.Conclusions C type ADHD has attention deficit and impulsivity and response inhibition defects.Ⅰ type ADHD has attention deficit and information processing capacity backward.Reaction rate of ADHD is more vulnerable to the impact of time-on-task.Two subtypes of ADHD children has different modes of cognitive impairment.