Effects of Expectancy on Cognitive Performance, Mood, and Psychophysiology in Healthy Adolescents and Their Parents in an Experimental Study

Placebo induced expectations of mood enhancement generate a positivity effect in emotional processing

A perceptual bias towards negative emotions is a consistent finding in mood disorders and a major target of therapeutic interventions. Placebo responses in antidepressant treatment are substantial, but it is unclear whether and how underlying expectancy effects can modulate response biases to emotional inputs. In a first attempt to approach this question, we investigated how placebo induced expectation can shape the perception of specific emotional stimuli in healthy individuals. In a controlled cross-over design, positive treatment expectations were induced by verbal instructions and a hidden training manipulation combined with an alleged oxytocin nasal spray before participants performed an emotion classification task on happy and fearful facial expressions with varying intensity. Analyses of response criterion and discrimination ability as derived from emotion-specific psychometric functions demonstrate that expectation specifically lowered participants’ threshold for identifying happy emotions in general, while they became less sensitive to subtle differences in emotional expressions. These indications of a positivity bias were directly correlated with participants’ treatment expectations as well as subjective experiences of treatment effects and went along with a significant mood enhancement. Our findings show that expectations can induce a perceptual positivity effect in healthy individuals which is probably modulated by top-down emotion regulation and which may be able to improve mood state. Clinical implications of these promising results now need to be explored in studies of expectation manipulation in patients with mood disorders.

Potential markers for predicting delayed encephalopathy in patients with acute carbon monoxide poisoning

BACKGROUND

Acute carbon monoxide poisoning (ACOP) commonly results in delayed neuropsychiatric sequelae (DNS). Currently, there are no reliable predictors. The aim of this article is to establish a practical model for predicting the development of delayed encephalopathy clinically.

METHODS

Retrospective analysis of clinical data were performed at a single institution for the past 6 years. 107 patients with ACOP were recruited, of who 67 developed DNS and 40 did not. Clinical characteristics of the patients were analyzed between the two groups. The risk factors associated with DNS development were screened to identify the potential markers for predicting DNS. A predictive model was then built, and the receiver operating characteristic (ROC) curve analysis was used to assess its predictive ability.

RESULTS

There were significant differences in 13 clinical features between the two groups. Four potential markers were identified. They were age, source of CO, Glasgow Coma Scale score and the initiation of HBOT. The potential predictive model showed an area under the curve (AUC) of 0.93 in the training set and 0.97 in the testing set.

CONCLUSIONS

Our model could calculate the probability of DNS after acute CO poisoning.