Lower estimated intelligence quotient is associated with suicide attempts in pediatric bipolar disorder

Approximately 20% of individual with pediatric bipolar disorder (PBD) have a lifetime history of suicide attempt. Some cognitive measures were associated with a suicide attempt, but no study has assessed the association of this event with the estimated intelligence quotient (IQ) in PBI. In adult Bipolar Disorder no association between IQ and suicidality was found, with different correlations between cognitive measures. There are studies in general population showing a negative correlation and others did not find any association. In Schizophrenia, IQ had a positive correlation with suicide attempt. So, the correlation between IQ and suicidality still controversial.

We recruited 63 children and adolescents younger than 18 years of age with PBD based on DSM-IV criteria from an outpatient clinic in Brazil. Manic and depressive symptoms were assessed with the YMRS and CDRS, respectively. Estimated IQ was assessed with the WISC-III. The presence or absense of suicidal attempt, clinical and demographic variables were assessed with the K-SADS-PL-W.

Patients who attempted suicide had lower estimated IQ compared to patients who did not attempt suicide (82.72 ± 18.70 vs. 101.0 ± 14.36; p = 0.009). This finding remained after correction for depressive symptoms and family income (OR = 0.94; 95% CI = 0.89 - 0.99; p = 0.029).

Small sample, reverse causality could not be discarded, we only used two subscales of the WISC-III to estimate intelligence.

Estimated IQ and suicide attempts were negative correlated in PBD. Future longitudinal and larger studies may confirm our findings.