Abstract
OBJECTIVES
This thesis examined three types of childhood adversity, low parental care, overprotection and abuse, as predictors of response to two types of depression treatment: antidepressant medication and psychotherapy. These three types of childhood adversity were also examined in association with adults who made a lifetime suicide attempt or engaged in non-suicidal self-injury (NSSI). Post-hoc analyses were conducted to explore for associations between patients who selected the most extreme responses, lowest or highest, on a pre-treatment measure of depression cognitions and their response to psychotherapy. These analyses were termed the “extreme responder hypothesis.”
METHOD
Two outpatient groups, recruited for separate but sequential clinical trials, comprised a sample of 372 adults with a primary diagnosis of major depressive episode. The first trial compared the antidepressant medications fluoxetine to nortriptyline (n = 195), and the second compared interpersonal psychotherapy (IPT) to cognitive behavioural therapy (CBT) (n = 177).
At baseline, all patients underwent a detailed clinical interview. The structured assessment was conducted by a trained clinician who asked a range of diagnostic questions including incidence of suicide attempts or self-harm; the research nurse asked about childhood abuse. Outcome data were gathered from these interviews, the clinician-rated Montgomery Åsberg Depression Rating Scale (MADRS), and the Clinical Global Impression Scale (CGI), as well as the self-report Parental Bonding Instrument (PBI).
OUTCOMES
In the medication trial, three outcomes were examined: whether or not the patient had an adequate trial of medication; the percentage improvement at six weeks as measured against MADRS baseline; and whether or not the patient achieved two months of sustained recovery, measured by the CGI at six months. In the psychotherapy trial, two outcomes were examined: whether or not the patient achieved a ≥60% improvement on the MADRS and percentage improvement at end-of-treatment as measured against MADRS baseline. Responses to suicide and NSSI questions were dichotomized outcomes.
KEY RESULTS
Medication trial:
• Low paternal care predicted an inadequate trial of medication.
• Maternal overprotection predicted poor patient response to treatment at six weeks and a lower rate of achieving two months of sustained recovery, measured at six months.
Psychotherapy trial:
• Maternal care showed a non-linear relationship with response across both therapies. Patients reporting intermediate levels of maternal care (versus low or high levels of care) responded best to psychotherapy.
• Across therapies, the interaction effect of maternal care by therapy and paternal protection by therapy were statistically significant.
• Maternal care and paternal protection levels were associated with a differential response to IPT but not CBT.
• The extreme responder hypothesis did not explain the downward response trend in patients who reported high maternal care.
Suicide attempts and NSSI:
• Low maternal care was associated with higher rates of lifetime suicide attempts.
• Low paternal care was associated with higher rates of NSSI.
Overall:
• Abuse — whether psychological, physical, or sexual — was not a robust predictor of any of the outcomes measured.
DISCUSSION
This thesis finds a modest association among low parental care, overprotection, and poor outcomes for adults with depression. The results suggest it is appropriate to conceptualize parental care and protection levels as contextual factors in treating a patient’s depression.
The experience of low parental care (emotional neglect) or overprotection in childhood, as measured by the Parental Bonding Instrument, has a greater impact on treatment response for adult depression and a stronger association with lifetime suicide attempts and NSSI than childhood abuse. These findings are supported by the literature on childhood attachment.