Are we afraid of the woods? - An investigation of the implicit and explicit fear reactions to forests.

The beneficial effects of nature exposure have been repeatedly documented and encourage frequent and regular contact with nature and especially highlight forests. However, in human history, forests have also been associated with negative emotions such as fear and were seen as dangerous environments. While existing literature could demonstrate that natural environments can evoke fear, the focus was on the explicit perception. Given that research has shown the significance of additional implicit processes in fear-related behaviour, we aim to explore the presence of an implicit fear response to forests. Therefore, in an online study, we investigated the explicit and implicit fear reactions to forests by a Northern German sample of N = 256. Using three explicit measurements, we investigated fear and danger perception on a semantic and visual level of the stimulus category "forest" compared to the human-made urban green space "park" and the urban setting "house". Additionally, we assessed the unconscious response tendencies towards the forest within three implicit tasks: Subliminal Priming Procedure (SPP), Affect Misattribution Procedure (AMP) and Approach-Avoidance Task (AAT). Within the analyzed sample, the subliminally presented word forest evoked a stronger positive valence response compared to park (SPP). In contrast to houses, the forest showed a stronger approach and weaker avoidance tendency (AAT). At the same time, both the three explicit and one implicit measurement (AMP) showed a stronger fear perception of forests compared to parks or houses. Considering the increasingly utilised beneficial effects of nature in interventions, these findings should be acknowledged when implementing nature exposure in interventions and treatments.

Differentiating paranoia and conspiracy mentality using a network approach.

Although mostly considered distinct, conspiracy mentality and paranoia share conceptual similarities (e.g., persecutory content, resistance to disconfirming evidence). Using self-report data from a large and multinational online sample (N = 2510; from the UK, the US, Hong Kong, Germany, and Australia), we examined whether paranoia and conspiracy mentality represent distinct latent constructs in exploratory and confirmatory factor analyses. Utilising network analysis, we then explored common and unique correlates of paranoia and conspiracy mentality while accounting for their shared variance. Across sites, paranoia and conspiracy mentality presented distinct, yet weakly correlated (r = 0.26), constructs. Both were associated with past traumatic experiences, holding negative beliefs about the self and other people, sleep problems, and a tendency to worry. However, paranoia was related to increased negative affect (i.e., anxiety) and decreased social support, whereas the opposite pattern was observed for conspiracy mentality (i.e., decreased anxiety and depression, increased social support). Paranoia and conspiracy mentality are related but not the same constructs. Their similar and distinct correlates point to common and unique risk factors and underlying mechanisms.

The role of leptin in rodent and human sleep: A transdiagnostic approach with a particular focus on anorexia nervosa.

This narrative review addressed to both clinicians and researchers aims to assess the role of hypoleptinemia in disordered sleep with a particular focus on patients with anorexia nervosa (AN). After introducing circadian rhythms and the regulation of circulating leptin, we summarize the literature on disordered sleep in patients with AN and in fasting subjects in general. We highlight novel single-case reports of substantially improved sleep within days after initiation of off-label metreleptin treatment. These beneficial effects are set in relationship to current knowledge of disordered sleep in animal models of an impaired leptin signaling. Specifically, both absolute and relative hypoleptinemia play a major role in animal models for insomnia, obstructive sleep apnea and obesity hypoventilation syndrome. We pinpoint future research required to complement our understanding of the role of leptin in sleep in patients with acute AN. Moreover, within the section clinical applications we speculate that human recombinant leptin may be useful for the treatment of treatment-resistant sleep-wake disorders, which are associated with (relative) hypoleptinemia. Overall, we stress the role of the hormone leptin in sleep.

The role of hypoleptinemia in the psychological and behavioral adaptation to starvation: Implications for anorexia nervosa.

This narrative review aims to pinpoint mental and behavioral effects of starvation, which may be triggered by hypoleptinemia and as such may be amenable to treatment with leptin receptor agonists. The reduced leptin secretion results from the continuous loss of fat mass, thus initiating a graded triggering of diverse starvation related adaptive functions. In light of leptin receptors located in several peripheral tissues and many brain regions adaptations may extend beyond those of the hypothalamus-pituitary-end organ-axes. We focus on gastrointestinal tract and reward system as relevant examples of peripheral and central effects of leptin. Despite its association with extreme obesity, congenital leptin deficiency with its many parallels to a state of starvation allows the elucidation of mental symptoms amenable to treatment with exogenous leptin in both ob/ob mice and humans with this autosomal recessive disorder. For starvation induced behavioral changes with an intact leptin signaling we particularly focus on rodent models for which proof of concept has been provided for the causative role of hypoleptinemia. For humans, we highlight the major cognitive, emotional and behavioral findings of the Minnesota Starvation Experiment to contrast them with results obtained upon a lesser degree of caloric restriction. Evidence for hypoleptinemia induced mental changes also stems from findings obtained in lipodystrophies. In light of the recently reported beneficial cognitive, emotional and behavioral effects of metreleptin-administration in anorexia nervosa we discuss potential implications for the treatment of this eating disorder. We postulate that leptin has profound psychopharmacological effects in the state of starvation.