Bilateral deep brain stimulation for the treatment of body dysmorphic disorder and obsessive-compulsive disorder.

Psychedelic substances, once shrouded in stigma and controversy, have recently garnered renewed attention for their potential therapeutic benefits (; ; ; ; ). Among these substances, psilocybin, found in certain species of mushrooms, has emerged as a promising candidate for mental health intervention (; ; ; ). Recent research has revealed compelling evidence of psilocybin's capacity to promote psychological wellbeing and induce enduring positive changes in personality traits (, ; ; ; ; ; ). These long-term modifications can be elicited by a single dose of psilocybin and are closely related to the quality of the subjective experience during the acute psychedelic state (; , , ; ; ). When generating altered states of consciousness, psilocybin can create peak experiences, also referred to as “mystical experiences”. These states are characterized by ego dissolution, forms of self-transcendence and inter-connectedness, feeling part of “all things”, oceanic boundlessness, and activation of positive affect sometimes referred to as awe and bliss (; ; ; ). These changes have been linked to enduring changes in personality, behavior, and wellbeing (). Moreover, neuroimaging studies have demonstrated that psilocybin may facilitate the activation of the core areas of what has been called the “social brain” () that evolved to facilitate attachment, social connectedness, friendship and cooperation (). These brain areas are particularly sensitive to social information in regard to the similarity, support and helpfulness of others and impact social cognition, and social reward systems, potentially offering insights into the therapeutic mechanisms of psilocybin (; ; ). In addition, compassion and compassion training have also been shown to impact many areas of the social brain, for example the ventral striatum, the (subgenual) anterior cingulate cortex, and the orbitofrontal cortex, along with neural networks associated with positive emotion and emotion regulation (; Kim et al., ; ). The Relaxed Beliefs Under pSychedelics (REBUS) model () provides a theoretical account of the mechanisms through which psychedelics produce positive therapeutic outcomes. Grounded in the Bayesian predictive processing framework (; ), REBUS proposes that psychedelics relax the precision-weighting of high-level priors (how strongly the brain relies on its top-down beliefs when interpreting reality), reducing the rigidity of maladaptive beliefs and increasing both neural and psychological flexibility. As with other facets of the psychedelic acute effects, this outcome is intricately tied to the context of the experience, also known as “set and setting”, the former referring to the brain state at the time of ingestion in regards to a sense of social safeness or unfamiliarity and threat, and the latter to the external environment (; ; ; ). While implementing settings conducive to the therapeutic action of psychedelics can be relatively straightforward, identifying and eliciting a favorable mindset remains more challenging, but in view of the processes involved in the evolution of the social brain (; ) and their psychophysiological mediators, it is likely to be linked to issues of social trust and care-protection. Herein lies the potential value of contemplative practices as primes because these practices stimulate core brain areas linked to feelings of social connectedness and caring (; Kim et al., ; ). These conditions have already shown promise in eliciting positive outcomes when combined with psilocybin and other classic serotonergic psychedelics (; ; ; ; ). Compassion-Focused Therapy (CFT; , , , , ; ) and Compassionate Mind Training (CMT) were developed to help individuals with high shame and self-criticism, who often respond poorly to traditional cognitive-behavioral interventions because of difficulties in generating self-soothing compassionate and supportive inner dialogue. Grounded in evolutionary psychology, attachment theory, and social mentality theory, CFT is a biopsychosocial therapy model that conceptualizes compassion as an evolved (stimulus-response guided) motivation, rooted in evolved caregiving systems. The evolution of caring helps the “cared-for” to regulate threat and seek social connectedness, affiliation and friendships as major evolved biosocial goals (). Compassion, defined as a “sensitivity to suffering and needs in self and others, with a commitment to alleviate and prevent it” (, ) therefore involves two parts: the stimulus which is the sensitivity to suffering and the response which is commitment to alleviating and preventing it. This motivation can operate through three flows: toward others, from others, and toward oneself; each supported by distinct psychophysiological mechanisms. These affiliative processes engage a balancing of the autonomic system with appropriate parasympathetic regulation via the vagus nerve, promoting states of safeness, affiliation, social trust, and flexible attention (; ). Meta-analytic evidenc