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Background.Minor stresses measured in daily life have repeatedly been associated with increased momentary psychotic experiences, both in individuals with psychotic disorders and in persons who are genetically at an increased risk for these disorders. Severe hearing impairment (SHI) is an environmental risk factor for psychotic disorder, possibly due to the experience of social exclusion. The aim of the current study is to investigate whether people with SHI exhibit higher levels of psychotic reactivity to social stressors in daily life than normal-hearing controls and whether this reactivity is associated with decreased baseline dopamine (DA) D2/3 receptor availability and/or elevated DA release following a dexamphetamine challenge.Method.We conducted an experience sampling study in 15 young adults with SHI and 19 matched normal-hearing controls who had previously participated in a single photon emission computed tomography study measuring DA D2/3 receptor availability and DA release in response to dexamphetamine.Results.The association between social stress and momentary psychotic experiences in daily life was stronger among SHI participants than among normal-hearing controls. Interactions between social stress and baseline striatal DA D2/3 receptor availability or DA release were not significant in multilevel models of momentary psychotic experiences including age, sex and tobacco use.Conclusions.While both elevated striatal DA release and elevated psychotic stress reactivity have been found in the same population defined by an environmental risk factor, SHI, their inter-relationship cannot be established. Further research is warranted to clarify the association between biological and psychological endophenotypes and psychosis risk. [ABSTRACT FROM AUTHOR]

BackgroundSerotonin and dopamine neurotransmitter systems are implicated in the regulation of mood, cognition and personality traits and their dysfunction is thought to be implicated in diverse psychopathologies. However, in healthy subjects the relationship between the serotonin and dopamine systems and neuropsychological functioning and personality traits is not clearly established. In the present study we investigated whether neuropsychological functioning, personality traits and mood states of a group of healthy subjects are associated with in vivo measures of serotonin transporters (SERTs) and dopamine transporters (DATs).MethodA total of 188 young healthy subjects underwent neuropsychological and subjective measurements of memory function, depression and impulsivity. Participants' SERT and DAT availability in predefined regions of interest were assessed using single photon emission computed tomography (SPECT) with the radiotracer [123I]β-CIT. Individual magnetic resonance imaging (MRI) scans served as anatomic reference.ResultsWe did not find any significant association between SERT or DAT availability and neuropsychological test performance or self-reported impulsivity and mood. There were no significant sex differences in SERT or DAT availability, but men performed significantly better on some tests of visuospatial functioning than women.ConclusionsRobust negative findings for striatal DAT availability seriously question earlier findings of positive associations between DAT availability and cognitive functions in healthy subjects. Our results also suggest that subcortical SERT availability is not associated with the neuropsychological functions and personality traits assessed. In summary, the present study suggests that neuropsychological and personality measurements in young healthy people are not associated with subcortical SERT or striatal DAT availabilities in the brain. [ABSTRACT FROM PUBLISHER]