Group Schema Focused Therapy for Eating Disorders with Comorbid Personality Disorders

In the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5;
(American Psychiatric Association, 2013) Eating Disorders (EDs) are
characterized by persisting disturbances in eating habits and over evaluation
of weight and shape. There are three subtypes specified in the DSM-5; anorexia
nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).
Additionally, if a patients* symptoms do not meet the full criteria of the
three specific ED diagnoses, they can be diagnosed with other specified feeding
or eating disorder (OSFED).
The lifetime prevalence differs per subtype. Lifetime prevalences in European
women are 1,7-6,3% for AN, <1-6,3% for BN and <1-2,3% for BED (Silén &
Keski-Rahkonen, 2022). For males, these rates are 0,3% (AN) to 1% (BN) (van
Eeden, 2021). Mortality rates in AN are one of the highest in all psychiatric
disorders (5.1%) (van Hoeken & Hoek, 2020).
Rigid personality traits are common within the ED population. Personality
disorders (PDs) are highly comorbid in EDs, with the highest proportion of
cluster C PDs in AN, and cluster B PDs for BN (Cassin & von Ranson, 2005;
Martinussen et al., 2017). According to the cohort study of Momen et al., there
was a relative risk of 4.5 for people with AN for comorbid personality disorder
(Momen, 2022). For people with other eating disorders this risk was 5.1. In a
meta-analysis conducted by Cassin & von Ranson (2005), perfectionism,
obsessive-compulsiveness, neuroticism, negative emotionality, harm avoidance,
low self-directedness, low cooperativeness, and traits associated with avoidant
PD were found in patients with AN or BN. AN (restrictive type) was found to be
more strongly associated with low novelty seeking, high constraint and
persistence, where BN was found to be more associated with high impulsivity and
sensation seeking. Personality traits in BED and AN (purging type), suggest
similarities to BN (Cassin & von Ranson, 2005). Comorbid PD has been shown to
adversely affect treatment outcomes (Farstad et al., 2016; Grilo, 2007). In
research on the natural course of eating disorders (Grilo et al., 2007); no
differences in rate of remission or relapse where found depending on a PD
diagnosis, except for avoidant PD among patients with EDNOS.
According to the Dutch standard of care, Cognitive Behavioural
Therapy-enhanced (CBT-e) is treatment of first choice for people with EDs,
where AN follows an extended version of the standard protocol used for BN and
BED (AkwaGGZ, 2017). CBT-e has been shown effective in a broad range of
patients (de Jong, 2016; Fairburn, 2009; Murphy et al., 2010), where CBT-Eb
(which targets major clinical problems such as mood intolerance, clinical
perfectionism and low self-esteem next to eating disorder features) was proven
to be more effective in those with more complex psychopathology (Fairburn,
2009).
Findings suggest high drop-out rates for treatment in patients with EDs (S.
Fassino, 2009). In his review he concluded that patients with more impulsivity
and/or emotional dysregulation are generally more at risk for dropout during
treatment. These patients also seem to have a genetic predisposition to
psychiatric and personality comorbidity and poorer treatment outcomes.
Although CBT-e is an effective treatment for EDs, a significant
proportion of patients does not respond well to CBT. It has been suggested that
the cognitive models do not sufficiently account for the roles of past
experiences and core (self)beliefs on eating disorder development and
maintenance (Schmidt, 2007). A therapy that does account for these factors, via
so-called early maladaptive schema*s (EMS), is Schema Focused Therapy (SFT). It
was originally introduced by Young as a response to the high dropout rates of
patients with personality disorders. The theory integrates elements of CBT
frameworks and other psychotherapeutical schools. Central in his theory are the
EMS, defined as implicit beliefs about the self and the relationship with the
environment (Young, 1990).
Research has shown that schema therapy is a promising intervention for complex
eating disorders (Pugh, 2015). It has been shown that ED patients have more EMS
than healthy controls, with no significant differences between the clinical ED
subgroups (Dingemans, 2006). Prelimenary research conducted by Simpson showed
important clinical improvements on both eating disordered symptoms as well as
severity of EMS and quality of life. Although this was a pilot study, it showed
that ED patients can benefit from SFT in a group setting (Simpson et al.,
2010). Our goal is to further investigate this effect. In this study a multiple
baseline case series design will be used.

The primary objective of the study is to examine the effects of group SFT for
an out-patient ED population, as assessed by change in both ED pathology as in
core self-beliefs.

Hypotheses:
1. There will be a decrease in dysfunctional core self-beliefs over time
2. There will be a decrease in ED symptoms

The secondary aim of this study is to examine the effect of group SFT for ED on
secondary clinical outcomes, namely self-reported general functioning.

3. There will be an increase of Quality of Life and psychosocial functioning

The proposed design is a multiple baseline case series, with a baseline varying
in length from 5 to 9 weeks, with 12 participants randomly allocated to each of
the 3 lengths (4 patients per condition). This design is proposed as an
alternative to the randomized control trial, because fewer participants are
required to establish an intervention effect.
The variation in baseline length offers the possibility to differentiate
between time effects and experimental effects of the treatment. After baseline,
a 30 week treatment phase follows, during which the group SFT protocol will be
applied. There will be 30 weekly measurements during the intervention phase,
plus 4 additional moments / periods of assessment: start of baseline, during
the pre-treatment baseline phase (5-9 weekly measurements), post-treatment (5-9
weekly measurements: frequency inversely related to those during the baseline
phase) and at follow-up (1 measurement: 3 months after completing the
intervention).

Thirty weekly sessions of 90 minutes of group SFT will be offered to
participating patients. The therapy will be based upon the protocol described
by Tjoa & Muste (2021), which in its turn is based on the schema therapy model
of Farrell & Shaw (2012, 2014).
Participating therapists are licensed psychologists, psychotherapists or
clinical psychologists that have undergone basic training in schema therapy.

Not applicable.