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

Abstract

Background

: 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).

Methods

: 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.

Results

: 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.

Conclusion

: 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.

Introduction

Bipolar disorder types I and II affect about 2% of the world's population, with subthreshold forms of the disorder affecting another 2% (Merikangas et al., 2007). Even with treatment, about 37% of patients relapse into depression or mania within 1 year, and 60% within 2 years (Gitlin et al., 1995). On the other hand, the prevalence of schizophrenia (SCZ) is estimated to be around 1% worldwide (Saha et al., 2005). SCZ follows a course characterized by prodromal symptoms in early adolescence, illness onset around 20s with several recurrence and exacerbations, resulting in chronic state of residual symptoms and functional impairment (Saha et al., 2005, Lieberman et al., 2013). Both disorders have been described as a life shortening condition (Hoang et al., 2011). Patients with a diagnosis of SCZ die 12–15 years before the average population while life expectancy has been reported to be decreased 9 years for patients with bipolar disorder (BD) (Saha et al., 2007, Crump et al., 2013). Given these findings, a thorough understanding of the early course of these diseases is important for timely accurate diagnosis and therapeutic intervention, as well as for the prevention of substantial burden of illness progression (Post and Kalivas, 2013, Carlborg et al., 2014), comorbidities (Young, 2009, Kredentser et al., 2014) and suicide attempts (Saha et al., 2007, Ishii et al., 2014).

Many patients with BD and SCZ are initially misdiagnosed especially in the early stages of both disorders (Young, 2009). The diagnostic difficulties between them are common (Vieta, 2010). The consequences of misdiagnosis can include worsening of manic or depression symptoms, increased drug resistance, reduced quality of life, and increased risk of suicide (Young, 2009). Early detection and appropriate differential diagnosis has potentially great benefits for prognosis and specific treatments preventing functional impairment (Hill et al., 2013).

The relationships with parents during childhood seem to have an important role in the children's psychosocial development (Ramchandani and Psychogiou, 2009) and could directly influence the ability to overcome a traumatic situation (Sagi-Schwartz et al., 2003, Lima et al., 2014). The study of parental bonding and its particularities in patients with SCZ and BD may shed some light to clarify the prodromal symptoms of each disorder, and helps in early differential diagnosis. Disturbances in this relationship have been associated with increased risk for a number of mental disorders and neurobiological dysfunctions (Enns et al., 2002, Klier and Muzik, 2004, Tyrka et al., 2008). For instance, low maternal warmth is one of the leading risk factors associated with the risk of mania relapse after recovery in child BD subjects (Geller et al., 2008, Geller et al., 2004).

Parental bonding characterizes a two-way process in which the child becomes emotionally attached to parents (Bowlby, 1977). The Parental Bonding Instrument (PBI) was developed to investigate parental behavior and healthy parent–child bonds during the first 16 years (Parker, 1979). PBI has two dimensions: care and overprotection (Parker, 1979). Previous PBI studies revealed that patients with several psychiatric disorders, such as major depressive disorder and obsessive compulsive disorder, are likely to have a low parental care score or a high overprotection score for the first 16 years (Narita et al., 2000, Wilcox et al., 2008, Willinger et al., 2002).

Our study aims to compare the parental bonding features among three groups: patients with BD and SCZ, and healthy controls. Our hypothesis is that there may be a difference in the quality of the bond between these two disorders, given the opposite clinical feature of BD and SCZ regarding affect modulation, which might be crucial for attachment and bonding development. This is the first study to perform such comparison.