"To co-operate or not?" Risky co-operative behavior in Schizophrenia and the effect of vasopressin

Social Psychopharmacology: Novel Approaches to Treat Deficits in Social Motivation in Schizophrenia

BACKGROUND AND HYPOTHESIS

Diminished social motivation is a negative symptom of schizophrenia and leads to severe functional consequences for many patients suffering from the illness. However, there are no effective medications available to treat this symptom. Despite the lack of approved treatments for patients, there is a growing body of literature on the effects of several classes of drugs on social motivation in healthy volunteers that may be relevant to patients. The aim of this review is to synthesize these results in an effort to identify novel directions for the development of medications to treat reduced social motivation in schizophrenia.

STUDY DESIGN

In this article, we review pharmacologic challenge studies addressing the acute effects of psychoactive drugs on social motivation in healthy volunteers and consider how these findings may be applied to deficits in social motivation in schizophrenia. We include studies testing amphetamines and 3,4-methylenedioxymethamphetamine (MDMA), opioids, cannabis, serotonergic psychedelics, antidepressants, benzodiazepines, and neuropeptides.

STUDY RESULTS

We report that amphetamines, MDMA, and some opioid medications enhance social motivation in healthy adults and may represent promising avenues of investigation in schizophrenia.

CONCLUSIONS

Given the acute effects of these drugs on behavioral and performance-based measures of social motivation in healthy volunteers, they may be particularly beneficial as an adjunct to psychosocial training programs in patient populations. It remains to be determined how these medications affect patients with deficits in social motivation, and in which contexts they may be most effectively administered.

Trust and psychosis: a systematic review and meta-analysis

BACKGROUND

Impaired trust in other humans is commonly seen in psychosis and it leads to poor societal functioning. However, examining trust behavior in an experimental setting is challenging. Investigators have used the trust game, a neuro-economic game to assess trust behavior in psychosis. However, the findings are inconsistent. Hence, we systematically reviewed the existing literature and conducted a meta-analysis to examine trust behavior in patients with psychosis, their relatives, and those at high risk for psychosis.

METHODS

We searched electronic databases for studies that have examined trust game in patients with psychosis, published up to November 2021. The primary outcome measure was the baseline trust in a trust game by patients and controls. The meta-analysis was performed if at least three data sets of control and patient groups were available for that measure/design. We conducted meta-analyses with a random-effects model. The results were described narratively wherever meta-analysis was not possible due to paucity of studies.

RESULTS

The searches across the databases including cross-references yielded 465 publications of which 10 studies were included in the final analysis. Baseline trust in the trust game was significantly lower in patients with psychosis compared to controls (SMD 0.39, 95% CI -0.14 to 0.64, p -0.002). However, a similar decrease in baseline trust was not present in relatives of patients (SMD 0.08, 95% CI -0.20 to 0.36, p -0.58).

CONCLUSIONS

The current meta-analysis suggests significant trust deficits in patients with psychosis. Future studies with a bigger sample size are required to understand the nature of trust deficits and factors affecting this impairment.

Nose-to-Brain Delivery of Therapeutic Peptides as Nasal Aerosols

Central nervous system (CNS) disorders, such as psychiatric disorders, neurodegeneration, chronic pain, stroke, brain tumor, spinal cord injury, and many other CNS diseases, would hugely benefit from specific and potent peptide pharmaceuticals and their low inherent toxicity. The delivery of peptides to the brain is challenging due to their low metabolic stability, which decreases their duration of action, poor penetration of the blood-brain barrier (BBB), and their incompatibility with oral administration, typically resulting in the need for parenteral administration. These challenges limit peptides’ clinical application and explain the interest in alternative routes of peptide administration, particularly nose-to-brain (N-to-B) delivery, which allows protein and peptide drugs to reach the brain noninvasively. N-to-B delivery can be a convenient method for rapidly targeting the CNS, bypassing the BBB, and minimizing systemic exposure; the olfactory and trigeminal nerves provide a unique pathway to the brain and the external environment. This review highlights the intranasal delivery of drugs, focusing on peptide delivery, illustrating various clinical applications, nasal delivery devices, and the scope and limitations of this approach.

A meta-analysis of hormone administration effects on cooperative behaviours: Oxytocin, vasopressin, and testosterone

The hormones oxytocin, vasopressin, and testosterone have been implicated in cooperative behaviours and have attracted increasing research interest for their potential to regulate human cooperation in both healthy and clinical populations. However, the behavioural effects of the administration of these hormones remain to be verified. The current analysis included 41 studies involving 3,269 participants with a narrow age range. We examined the administration effects of these hormones on cooperative behaviour and the regulatory effects of individual characteristics, hormone interventions, and task structure and context. Results revealed a moderate positive effect size of oxytocin intranasal administration, a large negative effect size of vasopressin intranasal administration, and nonsignificant effects of testosterone administration on cooperative behaviours. Participants with mental dysfunctions were less sensitive to oxytocin and vasopressin administration. Oxytocin administration was effective in an in-group situation and for initial choices, corroborating a Tit-for-Tat strategy.