Journal of Childhood & Developmental Disorders

Keywords

Bipolar disorder; Cognitive deficits; Major depressive disorder; Psychosis

Introduction

The presence of psychotic symptoms with mood disorders, such as Major Depressive Disorder (MDD) or Bipolar Disorder (BD), in children and adolescents seems to reflect severe manifestations of the disorders [1]. Research with adults with MDD and BD has generally revealed concomitant impairments in attention, processing speed, working memory, and executive functioning deficits [2,3]. Cognitive deficits in children and adolescents with severe mood disorders and psychosis have been less thoroughly examined [4-6].

Methods

In a study of the cognitive functioning of discharged child and adolescent psychiatric inpatients, we investigated the WISC– IV Full Scale IQ scores that were obtained following admission, and the working memory and processing speed of 80 children and youth, aged 8-17 years, with mood disorders, with and without accompanying psychotic features. Working memory was assessed by the WISC-IV digit span subtest, and processing speed was assessed via the Symbol Search and Coding Subtests. The psychiatric diagnosis on admission was utilized to identify diagnostic categories as well as the presence or absence of psychotic features. Based on DSM-IV criteria, the diagnostic groups included MDD (7 patients), BD (43 patients), Mood Disorder, Not Otherwise Specified (NOS) (30 patients). A total of 8 patients with MDD or BD had psychotic symptoms. No additional symptom inventory or severity scales were utilized. There were 43 females and 37 males, and the mean age was 14.21 years (SD=2.47).

Results

Sample size was deemed acceptable for planned analysis based on a priori power analysis (d=0.2, a=0.05) suggesting a sample size of 63 subjects. Differences in diagnosis and the presence or absence of psychotic features were generally unrelated to sex (p=0.82), race (p=0.81), and age although the patients with MD, (NOS) were slightly younger than the BD and MDD groups (p<0.001). Controlling for sex, age, and presence of psychotic symptoms, a Multivariate Analysis of Variance indicated no significant differences in cognitive functioning between the MDD and BD groups (F [8, 124]=0.46, p=0.88 ), or between those with MDD or BD (combined) and those with MD, NOS (F [4, 64]=0.06, p=0.99). The patients with MDD or BD and psychotic symptoms showed lower Full Scale IQ scores (F [2, 66]=3.50, p=0.036, n²=0.10) and worse working memory (F [2, 66]=5.19, p<0.008, n²=0.14) than those with MDD or BD without psychotic symptoms, even after the Bonferroni adjustment (adjusted risk a=0.013). Despite their low general cognitive ability, the patients with MDD or BD in addition to psychotic symptoms didn’t demonstrate significantly lower levels of Coding (p=0.35) and Symbol Search (p=0.47) scores than the other groups.

Conclusion

The results point to the importance of psychotic features associated with severe mood disorders in children and adolescents, as well as the need for additional research on developmental differences in mood disorders and cognition. If the findings of lower Full Scale IQ scores and working memory are replicated in larger studies of children and adolescents with severe mood disorders that utilize comprehensive neuropsychological assessments, the deleterious effect of cognitive deficits will need to be considered in supportive services and treatment interventions.

References

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