When Two Become One: Teens Living with an Eating Disorder and Borderline Personality Disorder


When Two Become One: Teens Living with an Eating Disorder and Borderline Personality Disorder


Young people diagnosed with an eating disorder (ED) have a higher risk of also being diagnosed with Borderline Personality Disorder (BPD), sometimes referred to as Emotionally Unstable Personality Disorder (EUPD). Studies have shown that young people who have been diagnosed with both an ED and BPD can have more severe symptoms of both, with a more complex presentation in the clinical setting. 

Teens living with ED and BPD may experience symptoms that are more severe than young people presenting with an ED alone. Depression, anxiety, impulsivity and mood dysregulation are often seen in young people diagnosed with both disorders. 

Eating disorders and borderline personality disorder together can present a complex clinical challenge. 

Borderline Personality Disorder in Teens 

BPD is believed to be the most common personality disorder that is found in young people linking with an ED. In order to understand young people who present with emotional, cognitive and behavioural concerns, specialist mental health teams will consider the current concerns and history of the young person. 

Borderline Personality Disorder in Under 18’s 

There is a rather outdated concept that is unfortunately still discussed in old school psychiatric circles, one which questions the ability to diagnose Borderline Personality Disorder in Under 18’s. 

Using DSM5-TR (Diagnostic and Statistical Manual of Mental Disorders), qualified mental health professionals are able to make a diagnosis in young people under 18 if a one-year pattern of immature personality development is noted with concerns in at least five of the following criteria:

  • Efforts to avoid real or imagined abandonment 
  • Unstable personal relationships 
  • Identity disturbance
  • Impulsivity
  • Suicidal and self-harming behaviours 
  • Affective instability 
  • Chronic feelings of emptiness 
  • Inappropriate intense anger 
  • Stress-related paranoid thinking

(American Psychiatric Association, 2022)

BPD can be reliably diagnosed in adolescents as young as 11 years. Just under 80% of teenagers and young people who present with suicidal or life ending thoughts and behaviours in Accident and Emergency Departments meet the criteria for diagnosis. (Guile, et al 2018).

Benefits of Early Diagnosis of Borderline Personality Disorder 

The early detection of borderline personality disorder (BPD) can greatly benefit young individuals and their families. Research has shown that early intervention can have a positive impact. An early diagnosis can lead to improved long-term results for children, teenagers, and young adults diagnosed with BPD.

Reluctance to Diagnose Can be Damaging to Young People

Borderline personality disorder has historically attracted stigma both within the medical profession and in the general public. This had led to a reluctance for some doctors to diagnose, or even discuss the possibility of diagnosis, with parents and young people. 

Ultimately, this leads to young people who may not receive the appropriate treatment at the right time, perhaps increasing the number of crisis interventions needed. Recent research at Harvard and McClean Hospital suggests that treating early in specialist programs and diagnosing well leads to a more positive long term outcome. 

Complex Trauma, Eating Disorders and Borderline Personality Disorder 

Complex Post Traumatic Stress Disorder (CPTSD) and BPD can often have very similar signs and symptoms. There are some variations and as a rule of thumb, it is possible to have experienced CPTSD without borderline personality disorder, however it is less likely the other way around. 

Many young people diagnosed with borderline personality disorder will have experienced traumatic events in their early years; it is important for parents to remember that there is no blame attached to the diagnosis. Trauma is not what happens to a young person but the way that they are able to process those events and relationships, for example, bullying, parental separation, the birth of a sibling, exam pressure, or medical trauma. Environmental factors are not standalone and often accompanied by genetic or familial links. An evaluation by a Child and Adolescent Psychiatrist who specialises in complex trauma, eating disorders and borderline personality disorder is always necessary. 

Why Do Teens with BPD Have a Higher Chance of Also Having an Eating Disorder?

Eating disorders and borderline personality disorder have an onset during the early-to late teens, with new cases less often seen in the 30’s and onwards. 

Studies show that young people with a combined diagnosis are more inclined to show traits of perfectionism, place a higher value on appearance and have a greater fear of rejection by others than their peers. 

Young people with a combined diagnosis are more likely to embark or or be interested in cosmetic surgery, be diagnosed with body dysmorphic disorder (BDD) and to have depression and social anxiety. 

Which Eating Disorders are More Common in BPD?

Research suggests that anorexia nervosa, bulimia nervosa, avoidant or resistant food intake disorder (ARFID), binge eating disorder and eating disorders not otherwise specified are all likely to occur alongside borderline personality disorder.

What is Rejection Sensitivity Dysphoria (RSD) in Teens and Young Adults?

Young people with high tended levels of rejection sensitivity may seek approval and validation more often than their peers. They may experience intense emotions when they feel left out, rejected or side-lined. This may prompt frequent explosive emotional outbursts. Young people may also have an increased fear of failure and very high expectations of themselves, with low self esteem and feelings of hopelessness. Children and teens with rejection sensitivity dysphoria may feel an intense sensitivity to criticism or perceived rejection or abandonment. 


Young people who are also diagnosed with autism and attention-deficit hyperactivity disorder (ADHD) may have increased rejection sensitivity. 

Therapy for Borderline Personality Disorder & Eating Disorders 


Dialectical behavioural therapy (DBT) is a useful set of tools for young people who are diagnosed with both eating disorders and borderline personality disorder. The Wave psychotherapy and skills groups are DBT based, teaching young people social skills to help stabilise difficult relationship dynamics at home, at school, with family and friends. 


Whilst DBT is useful, the persistence of highly sensitive rejection sensitivity following treatment indicates that other skills are also needed for young people and that DBT alone in the treatment of eating disorders combined with borderline personality disorder may not be sufficient. The intensive programs at The Wave combine DBT, with eating disorder specific treatments, MBT-ED, CBTe, IFS and EMDR. Mentalization based treatment is promising for the treatment of both eating disorders and personality disorders and the team at The Wave are trained in MBT by The Anna Freud Centre for Children and Families in London. 


What Does The Future Hold? 


Research into both eating disorders and borderline personality disorder is ongoing. Early interventions and early diagnosis is key to reducing the impact of both conditions on young people at home, in education and in development.  At present there are no medications specifically to treat borderline personality disorder, however there are medications that can help with some of the more troubling symptoms. Antidepressants, antipsychotic medication and mood stabilisers can be beneficial when combined with psychotherapy. 


Residential Treatment Programs for Borderline Personality Disorder and Eating Disorders


Treatment for the combined diagnosis of BPD and ED can be lengthy, with several levels of care needed to adequately prepare young people with skills for life. Therapy, psychiatry, psychoeducation and social skills are all needed and in many instances most appropriately delivered in a residential or inpatient setting. Where weight restoration is needed, this would require specialist eating disorder Medically Managed Programs, like Indigo at The Wave. Indigo is a specialist program housed inside The Wave main programs for the treatment of complex eating disorders and complex borderline  presentations, including self harm and thoughts of suicide. 

Fiona - The Wave Clinic

Fiona Yassin is the founder and clinical director at The Wave Clinic. She is a U.K. and International registered Psychotherapist and Accredited Clinical Supervisor (U.K. and UNCG).

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