RESUMEN
Mindfulness interventions have been found to lower anxiety. However, the current literature has not adequately considered the role of its individual components and of placebo effects. In an online experiment using a balanced placebo design, we aimed to disentangle effects of decentering, a key component of mindfulness, and expectations, a key component of placebo effects, on anxiety related to the COVID-19 pandemic. One hundred twenty-eight adults were randomly assigned to one of four groups: placebo/mindful decentering, placebo/sham decentering, sham/mindful decentering, and sham/sham decentering. Instructions were provided using standardized audio instructions. Current anxiety was assessed pre- and postintervention with the Short State version of the State-Trait Anxiety Inventory. Mindful decentering was found to reduce anxiety postintervention, as compared to sham decentering, regardless of induced expectations regarding its effectiveness. Participants in the mindful decentering group also mentioned more decentering-related words than those in the sham decentering group. These findings indicate that a short, standardized, and online mindful decentering intervention can effectively decrease pandemic-related anxiety independently of one's expectations. These findings provide insights into the efficacy of the individual elements of mindfulness, highlighting decentering as an effective active component for anxiety relief. Moreover, these findings suggest that, in a nonclinical sample, individuals can apply mindful decentering with minimal training.
Asunto(s)
Ansiedad , COVID-19 , Atención Plena , Humanos , Atención Plena/métodos , Masculino , Femenino , Adulto , COVID-19/psicología , Ansiedad/terapia , Ansiedad/psicología , Adulto Joven , Efecto Placebo , Persona de Mediana EdadRESUMEN
The dopamine hypothesis of schizophrenia posits that elevated striatal dopamine functioning underlies the development of psychotic symptoms. Chronic exposure to social stressors increases psychosis risk, possibly by upregulating striatal dopamine functioning. Here we systematically review single photon emission computed tomography (SPECT) and positron emission tomography (PET) studies that examined the relationship between chronic social stress exposure and in vivo striatal dopamine functioning in humans. We searched the scientific databases PubMed and PsycINFO from inception to August 2023. The quality of the included studies was evaluated with the ten-item Observational Study Quality Evaluation (PROSPERO: CRD42022308883). Twenty-eight studies were included, which measured different aspects of striatal dopamine functioning including dopamine synthesis capacity (DSC), vesicular monoamine transporter type 2 binding, dopamine release following a pharmacological or behavioral challenge, D2/3 receptor binding, and dopamine transporter binding. We observed preliminary evidence of an association between childhood trauma and increased striatal DSC and dopamine release. However, exposure to low socioeconomic status, stressful life events, or other social stressors was not consistently associated with altered striatal dopamine functioning. The quality of available studies was generally low. In conclusion, there is insufficient evidence that chronic social stressors upregulate striatal dopamine functioning in humans. We propose avenues for future research, in particular to improve the measurement of chronic social stressors and the methodological quality of study designs.