4. Examples of types of psychological interventions and how they might work.

Psychological intervention	How the intervention may work
Cognitive behaviour therapy (CBT)	CBT‐based treatments place emphasis on encouraging the patient to challenge their core beliefs and thoughts in order to gain insight into how these influence their feelings and behaviour (Bateman 2004a; Henwood 2015).
Cognitive analytic therapy (CAT)	CAT utilises ideas from psychodynamic psychotherapy and cognitive therapy (Denman 2001). CAT encourages patients to identify and change learned attitudes and beliefs about themselves and how these impact on their patterns of relating to others.
Dialectical behavioural therapy (DBT)	DBT is a complex psychological intervention developed using some of the principles of CBT (Linehan 1993). DBT provides individuals with skills training in four modules (i.e. mindfulness, distress tolerance, emotion regulation, interpersonal effectiveness).
Psychoanalytic therapy or dynamic psychotherapy	The British Psychoanalytic Council defines psychoanalytic therapies as "a range of therapeutic treatments derived from psychoanalytic ideas and methods and a critical appreciation of the effect of childhood experiences on adult personality development" (British Psychoanalytical Council 2018; quote, p 2). (see also Piper 1993, Winston 1994, Bateman 2001 and Leichsenring 2003).
Mentalisation‐based therapy (MBT)	MBT has developed from attachment theory and aims to help patients identify and reflect on what they, and others are feeling and why, in order to better regulate their behaviour and emotions (Bateman 2004b).
Schema therapy (ST)	In ST, the therapist helps the patient identify long‐standing, self‐defeating patterns of thinking, feeling and behaving (‘schemas’) and develop healthier alternatives to replace them (Young 2003).
Nidotherapy	Nidotherapy is a formalised, planned method for achieving environmental change to minimise the effect of the participant’s difficulties upon themselves and others. Unlike most other therapies, it aims to fit the immediate environment to the patient, rather than change the patient to cope in the existing environment (Tyrer 2007). In order to achieve this, a detailed psychological formulation is developed for the individual participant (Tyrer 2005a).
Therapeutic community (TC) treatment	TC treatments involve participants engaging in group psychotherapy whilst being involved in a shared, therapeutic environment. This provides them with an opportunity to “explore intrapsychic and interpersonal problems and find more constructive ways of dealing with distress” (Campling 2001, quote, p 365). (see also Lees 1999).
Contingency management	Contingency management is based on the psychological principles of behaviour modification and aims to incentivise and reinforce changes in behaviour through the use of financial (or other rewards) that are of value to the patient. (Petry 2011).

^{CAT = Cognitive analytic therapy
CBT = Cognitive behaviour therapy
DBT = Dialectical behavioural therapy
MBT = Mentalisation‐based therapy
ST =  Schema therapy 
TC = Therapeutic community}