On the interaction between sad mood and cognitive control: the effect of induced sadness on electrophysiological modulations underlying Stroop conflict processing.

The present study employed high-density ERPs to examine the effect of induced sad mood on the spatiotemporal correlates of conflict monitoring and resolution in a colour-word Stroop interference task. Neuroimaging evidence and dipole modelling implicates the involvement of the anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) regions in conflict-laden interference control. On the basis that these structures have been found to mediate emotion-cognition interactions in negative mood states, it was predicted that Stroop-related cognitive control, which relies heavily on anterior neural sources, would be affected by effective sad mood provocation. Healthy participants (N=14) were induced into transient sadness via use of autobiographical sad scripts, a well-validated mood induction technique (Liotti et al., 2000a, 2002). In accord with previous research, interference effects were shown at both baseline and sad states while Stroop conflict was associated with early (N450) and late (Late Positive Component; LPC) electrophysiological modulations at both states. Sad mood induction attenuated the N450 effect in line with our expectation that it would be susceptible to modulation by mood, given its purported anterior limbic source. The LPC effect was displayed at the typical posterior lateral sites but, as predicted, was not affected by sad mood. However, frontocentral LPC activity-presumably generated from an additional anterior limbic source-was affected at sad state, hinting a role in conflict monitoring. Although the neurophysiological underpinnings of interference control are yet to be clarified, this study provided further insight into emotion-cognition interactions as indexed by Stroop conflict-laden processing.

Electrophysiological evidence for abnormal error monitoring in recurrent major depressive disorder.

Previous neuroimaging work has identified anterior cingulate cortex (ACC) abnormalities in recurrent major depressive disorder (MDD), implicating a persistent underlying predisposition to depression. Error-monitoring studies in MDD, as indexed by error-related negativity (ERN), have yielded conflicting results, probably because of task differences or confounds in patient samples. ERN patterns were examined in remitted (n=19) and acutely depressed (n=17) patients, classified as a function of illness stage, and their matched controls in a go/no-go task using high-density ERPs. Results showed an abnormally larger ERN (p<.05) in remitted patients, especially in younger cases. Overall, ERN was found to decrease with age across all groups. The findings of increased ERN in remitted depression may implicate an overactive ACC associated with a hypervigilant error-monitoring system. The observed tendency of ERN reduction in a severe depressive state failed to reach statistical significance.

Official psychiatric morbidity and the incidence of schizophrenia 1881-1994.

BACKGROUND: We assess claims that the documented rise in psychiatric morbidity during the nineteenth and twentieth centuries was associated with an increasing incidence of schizophrenia. METHOD: Cross-sectional epidemiological comparison of the incidence of schizophrenia in one urban, industrialized community at three points over more than 100 years using new data from 1881-1902 and two pre-existing datasets, 1978-1980 and 1992-1994. For 1881-1902, 34 cases of schizophrenia were obtained through retrospective diagnosis, using Research Diagnostic Criteria, of a random 14.5% sample of first admissions to Nottingham Asylum (n = 330). Inter-rater reliability and leakage analyses were performed. The administrative incidence for all three studies was directly standardized against 1991 census data. Local statistics on total psychiatric morbidity in Nottingham were taken from the asylum superintendent's register and recent data from the Office of National Statistics. RESULTS: Official local and national rates of total psychiatric morbidity increased exponentially. There was no significant change in the incidence of schizophrenia over the 114-year period 1881-1994. CONCLUSIONS: The rise in both local and national official statistics of psychiatric morbidity 1881-1994 was not associated with a significant increase in the incidence of schizophrenia. Stability in the epidemiology of schizophrenia at a geographical level is found despite important demographic changes.