Psilocybin restrains activity-based anorexia in female rats by enhancing cognitive flexibility: contributions from 5-HT1A and 5-HT2A receptor mechanisms.

Psilocybin has shown promise for alleviating symptoms of depression and is currently in clinical trials for the treatment of anorexia nervosa (AN), a condition that is characterised by persistent cognitive inflexibility. Considering that enhanced cognitive flexibility after psilocybin treatment is reported to occur in individuals with depression, it is plausible that psilocybin could improve symptoms of AN by breaking down cognitive inflexibility. A mechanistic understanding of the actions of psilocybin is required to tailor the clinical application of psilocybin to individuals most likely to respond with positive outcomes. This can only be achieved using incisive neurobiological approaches in animal models. Here, we use the activity-based anorexia (ABA) rat model and comprehensively assess aspects of reinforcement learning to show that psilocybin (post-acutely) improves body weight maintenance in female rats and facilitates cognitive flexibility, specifically via improved adaptation to the initial reversal of reward contingencies. Further, we reveal the involvement of signalling through the serotonin (5-HT) 1 A and 5-HT2A receptor subtypes in specific aspects of learning, demonstrating that 5-HT1A antagonism negates the cognitive enhancing effects of psilocybin. Moreover, we show that psilocybin elicits a transient increase and decrease in cortical transcription of these receptors (Htr2a and Htr1a, respectively), and a further reduction in the abundance of Htr2a transcripts in rats exposed to the ABA model. Together, these findings support the hypothesis that psilocybin could ameliorate cognitive inflexibility in the context of AN and highlight a need to better understand the therapeutic mechanisms independent of 5-HT2A receptor binding.

Are there differences in the attitudinal body image between adolescent anorexia nervosa and bulimia nervosa?

OBJECTIVE: Body image dissatisfaction is as well a risk factor for eating disorders (ED) and a central feature of ED. The exact nature of body image in adolescent ED is still debated. This study examined attitudinal body image in adolescent anorexia nervosa (AN) and bulimia nervosa (BN), and the association of age, maturational timing, duration of eating disorder, actual weight and general psychological distress with the attitudinal body image in ED. METHODS: The study group consisted of an outpatient clinical sample of adolescents attending for assessment because of eating disorders. The attitudinal body image of 57 adolescents (girls) aged 14-21 years was studied at the beginning of the treatment. The attitudes to body shape, body size, appearance, tone and femininity were studied by a Likert format scale and by the body dissatisfaction (BD) and drive for thinness scales (DT) from EDI-2 inventory. RESULTS: Bulimics reported more body image dissatisfaction than anorectics. In multivariate analyses BN and higher general psychological distress had strong associations with body image dissatisfaction. Longer duration of ED and earlier menarche were also associated with negative body image. DISCUSSION: Attitudinal body image differs between adolescent AN and BN. The psychological distress has a great impact on body image in ED, which should be taken into account in assessment and in treatment interventions.

Clinical use of neck isometric strength measurement in rehabilitation.

The purpose of this study was to evaluate for diagnostic purposes the isometric strength of the neck flexor and extensor muscles in 56 patients with neck and shoulder pain and to quantify the effect of a specific rehabilitation program. An isometric measurement protocol was performed at the beginning and at the end of a 3-week rehabilitation program that included physiotherapy, stretching, aerobic exercises, and circuit training to improve arm, shoulder, and neck muscle strength. In the beginning, mean neck flexor muscle isometric strength was 83N (+/- 48 SD) and extensor muscle strength 158N (+/- 76 SD), whereas after rehabilitation the strength measurements were 117N (+/- 43 SD) and 207N (+/- 84 SD) respectively. There was a significant increase in the ability to push forward and backward, which correlated with the lessening of neck pain and disability found at the end of the program (p < .05). Isometric strength measurement is a useful and practical method of objectively showing a functional improvement in response to rehabilitation.