On the Affective Story Task, the PBD group performed significantly more poorly than matched controls in the positive (χ2=5.81, p<0.05) and negative (χ2=5.52, p<0.05) story conditions, and there was a trend (χ2=4.02, p=0.06) towards poorer performance in the neutral condition (see for the mean percentage correct in each group). Differences in performance between each of the affective conditions (i.e. positive and negative) and the neutral condition were computed separately for the PBD and control groups. PBD patients performed significantly more poorly in the negative story condition than in the positive story condition (χ2 = 7.23, p<0.01), and there was a trend towards poorer performance in the negative condition compared to the neutral condition (χ2 = 3.60, p = 0.09). There were no significant differences between performance in the positive compared to the neutral condition (χ2 = 1.89, p = 0.21). Among healthy comparison subjects, there were no significant differences between any of the three conditions (p>0.05).
Mean percentage correct (standard deviation) and significance values for the healthy comparison and pediatric bipolar disorder (PBD) subjects on the Affective Story Task and the Hinting Task
In the PBD group, increased symptoms of mania on the YMRS were associated with failure to answer the false-belief question correctly in the negative story condition of the Affective Story Task (r =−0.44, p<0.05). There were no significant associations between YMRS scores and performance on the positive (r=−0.28, p = 0.19) or neutral (r=−0.31, p = 0.15) story conditions among PBD youth. There were also no significant associations between increased symptoms of depression on the CDRS-R and performance on the positive (r =−0.30, p = 0.16), negative (r = 12, p = 0.58) or neutral (r = 0.16, p = 0.46) conditions. Among controls, there were no significant associations between YMRS and CDRS-R scores and performance on the Affective Story Task. Performance on the Affective Story Task was not associated with age or age at first diagnosis (PBD only) for PBD youth or controls (p’s >0.05). Age was also not correlated with YMRS or CDRS-R scores in either group (p’s >0.05).
On the Hinting Task, the PBD group scored significantly lower than controls [t(37) =4.37, p<0.001]. Among PBD patients, poorer Hinting Task performance was correlated significantly with younger age (r = 0.66, p<0.001) and an earlier age at first diagnosis (r = 0.58, p<0.01). By contrast, among healthy comparison subjects, there was no significant relationship between age and performance on this task (r = 0.08, p = 0.74). Among PBD patients, higher YMRS scores were associated with poorer performance on the Hinting Task (r = 0.57, p<0.01). There were no significant relationships between CDRS-R scores and.Hinting Task performance in the PBD group (r=−0.04, p = 0.84).
To examine the effects of co-morbid ADHD status on ToM among PBD youth, a series of analyses were performed examining differences between PBD youth with co-morbid ADHD versus those without ADHD. There were no significant group differences between PBD+ADHD and PBD-only subjects on any of the Affective Story Task conditions [positive (χ2 = 0.26, p = 0.61), negative (χ2 = 1.33, p = 0.25), neutral (χ2 = 0.53, p = 0.47)]. However, significant differences were observed on the Hinting Task [t(24) =2.70, p <0.05], with the PBD+ADHD group performing significantly more poorly (mean = 12.33, s.d. =4.13) than the PBD-only group (mean = 16.27, s.d. = 2.94). PBD + ADHD youth also had significantly higher symptoms of mania on the YMRS [t(25) =4.40, p<0.001] compared to PBD-only youth. There were no significant differences on CDRS-R scores between the PBD + ADHD and PBD-only groups.
Differences on the ToM tasks between BD types I and II were also examined. There were no significant differences between BD I and II youth on the positive (χ2 = 0.65, p = 0.68) or negative (χ2 = 0.47, p = 0.69) Affective Story Task conditions, and there was a trend towards poorer performance among BD I youth in the neutral condition (χ2 = 3.48, p = 0.09). On the Hinting task, the BD I group (mean = 12.50, s.d. =4.75) performed significantly more poorly than the BD II group (mean = 15.75, s.d. = 2.38) [t(24) =2.25, p<0.05]. There was a trend towards greater manic symptomatology on the YMRS in the BD I group [t(24) = 1.84, p = 0.08]. There were no significant differences between youth with BD I and BD II on the CDRS-R [t(24) = 1.23, p = 0.23].