Being one of the most common mental disorders, Major Depressive Disorder (MDD), also referred to as Unipolar Depression, is characterized by persistent low mood across situations, loss of interest in activities and feelings of extreme hopelessness. MDD is linked with significant disturbance in life quality and interpersonal relationships as well as increased risk of mortality (Zlotnick, Kohn, Keitner & Della Grotta, 2000; Cuijpers & Smit, 2002). Having taken into consideration the adverse and life-threatening aspects of MDD, research has paid great attention to its risk and protective factors and their interaction, while yet numerous theories were developed to explain and elaborate on the onset, maintenance and treatment of depression (e.g. Beck, 1967; Coyne, 1976b).
Psychodynamic theories are descendants of Sigmund Freud’s psychoanalytic theory which focused predominantly on the internal structures of mind and explained psychopathology with regards to dynamics of the structures. The contribution of psychodynamic theories was the focus on the interplay between intrapsychic dynamics and interpersonal relationships (Meehan & Levy, 2009).
Even though there is diversity among psychodynamic theories, the major role of early interpersonal relationships and their internalizations forming personality and thus susceptibility to psychopathology is agreed upon. Attachment theory, proposed by Bowlby (1969), lays extensive emphasis on the early relationship with the primary caregiver and the foundation this relationship provides for future relational, emotional and cognitive functioning. According to attachment theory (Bowlby, 1969; Bowlby & Ainsworth, 1991), attachment quality is shaped by caregiver’s response to child’s distress and provision of gratification to child’s needs. Through interactions with the caregiver then, the child develops internal working models with mental representations of self and others that extend into adulthood and draws on these models in the future (Bowlby, 1969; 1980). A responsive and available primary caregiver becomes a safe base for the child to rely on and encourages child to explore, thus, the child becomes securely attached. Whereas in dyadic relationships where the primary caregiver is unavailable in times of distress, irresponsive to child’s needs or unpredictable in his/her behavior, the child beomes insecurely attached. Being formed during times of distress, attachment is argued to have predictive value for one’s affect regulation strategies, stress management skills, behavioral self-regulation skills and self-worth (Mikulincer & Shaver, 2007; Morely & Moran, 2011). It is well-documented that especially insecure attachment, as the outcome of early maladaptive child-caregiver interactions, predicts ineffective emotion regulation strategies and deficient interpersonal functioning (e.g. Field, 1994; Contreras & Kerns, 2000), thus renders the individual more vulnerable to psychopathology (Cummings & Cicchetti, 1990; Morely & Moran, 2011; Abaied & Rudolph, 2014).
Due to the supposed predictive value of insecure attachment, and the shared symptomatology between insecure attachment and depression, the two phenomena were extensively studied in relation with each other. Cross-sectional studies provide support for a significant correlation between insecure attachment and depressive symptoms (e.g. Pettem, West, Mahoney & Keller, 1992; Abela, Hankin, Haigh, Adams, Vinokuroff & Trayhern, 2005). But the cross-sectional design becomes a preclusion for making inferences regarding the proposed causality between insecure attachment and depression. In other words, it is hard to refer to the direction of the effect of insecure attachment on the onset of depression.
Interestingly, most of the research is conducted in cross-sectional design and there is only a small proportion conducted in longitudinal design, comparing depressive symptoms assessed at different time points. The longitudinal studies provide prospective inferences about the direction of the correlation, or in other words the causality (e.g. Roberts, Gotlib & Kassel, 1996; Allen, Porter, McFarland, McElhaney, & Marsh, 2007; Lee & Hankin, 2009; Monti & Rudolph, 2014). Closer investigation of longitudinal studies reveals that most of these studies lack an interview-based diagnosis of MDD and only govern self-measures of depressive symptoms. This again, hinders the strength of conclusions drawn, regarding the effect of insecure attachment on depression. Although cost-effective and time-efficient, self-reports of depression fail to assess the psychopathological aspects that are only apparent to others than self (Paykel & Norton, 1986). The significant results of questionnaires administered to assess depressive symptoms may say something about seasonal affective disorder (SAD) or any type of non-full-blown depression but in any case, diagnosis of MDD is hardly possible without a clinician administered interview. Recently, Stuart et al. (2014) compared self-report and structured clinical interview in the identification of depression and found that the level of aggreement between self-reports and interviews were only moderate and that self-report methods provide a limited degree of confidence in the identification of depression.
Current study is the meta-analysis of research composed of (1) longitudinal studies that include (2) an interview-based diagnosis of MDD that investigate the predictive value of (3) insecure attachment. The strict inclusion criteria provides conservative results regarding the effect of insecure attachment on MDD.