Differences in parental bonding between schizophrenia and bipolar disorder: Evidence of prodromal symptoms?

The Parental Bonding Instrument (PBI) examines parent-child bonds and attachment during the first 16 years. Our study aims to compare PBI scores between patients with schizophrenia and bipolar disorder (BD).

We analyzed PBI scores in 59 patients with schizophrenia, 36 with BD and 52 healthy controls using ANCOVA, with age, gender and years of education as covariates. Bonferroni correction was used to adjust for multiple comparisons. PBI has maternal and paternal scores, each one with two domains: care and overprotection.

In PBI maternal and paternal care domains, patients with schizophrenia showed significantly higher scores when compared with BD patients (p<0.001). However, when compared with healthy controls, patients with schizophrenia only showed significantly higher scores of PBI maternal care domain (p=0.037). BD patients showed significantly lower PBI care scores compared with healthy controls (maternal score: p=0.016; paternal score: p<0.001). In PBI maternal and paternal overprotection domain, BD patients showed significantly higher scores compared with patients with schizophrenia (p=0.004; p=0.021) and healthy controls (p=0.014; p=0.008); while no significant difference was observed between patients with schizophrenia and healthy controls. "P values" are according to Bonferroni correction.

There are significant differences in the perception of attachment between schizophrenia and BD. This finding may shed some light to better understand the prodromal symptoms of each disorder.