Cannabis-Associated Psychotic-like Experiences Are Mediated by Developmental Changes in the Parahippocampal Gyrus

OBJECTIVE

Cannabis consumption during adolescence has been reported as a risk factor for psychotic-like experiences (PLEs) and schizophrenia. However, brain developmental processes associated with cannabis-related PLEs are still poorly described.

METHOD

A total of 706 adolescents from the general population who were recruited by the IMAGEN consortium had structural magnetic resonance imaging scans at both 14 and 19 years of age. We used deformation-based morphometry to map voxelwise brain changes between the two time points, using the pairwise algorithm in SPM12b. We used an a priori region-of-interest approach focusing on the hippocampus/parahippocampus to perform voxelwise linear regressions. Lifetime cannabis consumption was assessed using the European School Survey Project on Alcohol and other Drugs (ESPAD), and PLEs were assessed with the Comprehensive Assessment Psychotic-like experiences (CAPE) tool. We first tested whether hippocampus/parahippocampus development was associated with PLEs. Then we formulated and tested an a priori simple mediation model in which uncus development mediates the association between lifetime cannabis consumption and PLEs.

RESULTS

We found that PLEs were associated with reduced expansion within a specific region of the right hippocampus/parahippocampus formation, the uncus (p = .002 at the cluster level, p = .018 at the peak level). The partial simple mediation model revealed a significant total effect from lifetime cannabis consumption to PLEs (b = 0.069, 95% CI = 0.04-0.1, p =2 × 10^-16), as well as a small yet significant, indirect effect of right uncus development (0.004; 95% CI = 0.0004-0.01, p = .026).

CONCLUSION

We show here that the uncus development is involved in the cerebral basis of PLEs in a population-based sample of healthy adolescents.

Neural Correlates of Failed Inhibitory Control as an Early Marker of Disordered Eating in Adolescents

BACKGROUND

Binge eating and other forms of disordered eating behavior (DEB) are associated with failed inhibitory control. This study investigated the neural correlates of failed inhibitory control as a potential biomarker for DEB.

METHODS

The study used prospective longitudinal data from the European IMAGEN study adolescent cohort. Participants completed baseline assessments (questionnaires and a brain scan [functional magnetic resonance imaging]) at 14 years of age and a follow-up assessment (questionnaires) at 16 years of age. Self-reported binge eating and/or purging were used to indicate presence of DEB. Neural correlates of failed inhibition were assessed using the stop signal task. Participants were categorized as healthy control subjects (reported no DEB at both time points), maintainers (reported DEB at both time points), recoverers (reported DEB at baseline only), and developers (reported DEB at follow-up only). Forty-three individuals per group with complete scanning data were matched on gender, age, puberty, and intelligence (N = 172).

RESULTS

At baseline, despite similar task performance, incorrectly responding to stop signals (failed inhibitory control) was associated with greater recruitment of the medial prefrontal cortex and anterior cingulate cortex in the developers compared with healthy control subjects and recoverers.

CONCLUSIONS

Greater recruitment of the medial prefrontal and anterior cingulate regions during failed inhibition accords with abnormal evaluation of errors contributing to DEB development. As this precedes symptom onset and is evident despite normal task performance, neural responses during failed inhibition may be a useful biomarker of vulnerability for DEB. This study highlights the potential value of prospective neuroimaging studies for identifying markers of illness before the emergence of behavior changes.

[Functional somatic syndromes: A comprehensive cognitive model]

Functional somatic syndromes are frequent in general and specialized medicine practices. Several treatments can be useful. However, the treatment program is often hampered by patients' reluctance to acknowledge the diagnosis because of erroneous lay representations. Recent advances in cognitive science offer a new understanding of the pathophysiology of functional somatic disorders, making this diagnosis more acceptable for patients and caregivers. Simply explained with practical examples, the Bayesian model in particular provides some insights into the underlying cognitive mechanisms of functional somatic syndromes and their treatments. Advantages of this approach are twofold: it is consistent with current scientific knowledge and it can facilitate the physician-patient relationship.

Association between depression and anemia in otherwise healthy adults

OBJECTIVE

It remains debated whether anemia is associated with depression, independently of physical health factors. We report a large-scale cross-sectional study examining this association in adults free of chronic disease and medication from the general population.

METHOD

Hemoglobin levels were measured among 44 173 healthy participants [63% men; mean [standard deviation] age = 38.4 (11.1) years] from the 'Investigations Préventives et Cliniques' (IPC) cohort study. Depression was measured with the Questionnaire of Depression 2nd version, Abridged. Logistic regression analyses were performed to examine the association between anemia and depression, while adjusting for a wide range of sociodemographic characteristics and health-related factors (i.e., sex, age, living status, education level, occupational status, alcohol intake, smoking status, physical activity, and body mass index).

RESULTS

Depressed participants were significantly more likely to have anemia compared to non-depressed participants, even after adjustment for sociodemographic and health-related variables [odds ratio = 1.36; 95% confidence interval = (1.18; 1.57)]. Anemia prevalence increased with depression severity, suggesting a dose-response relationship (P for trend <0.001).

CONCLUSION

In healthy adults from the general population, we found a significant and robust association between depression and anemia. Further studies are needed to assess the longitudinal relationship between both conditions and determine the mechanisms underlying this association.

Resilience and corpus callosum microstructure in adolescence

BACKGROUND

Resilience is the capacity of individuals to resist mental disorders despite exposure to stress. Little is known about its neural underpinnings. The putative variation of white-matter microstructure with resilience in adolescence, a critical period for brain maturation and onset of high-prevalence mental disorders, has not been assessed by diffusion tensor imaging (DTI). Lower fractional anisotropy (FA) though, has been reported in the corpus callosum (CC), the brain's largest white-matter structure, in psychiatric and stress-related conditions. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents.

METHOD

Three groups of adolescents recruited from the community were compared: resilient with low risk of mental disorder despite high exposure to lifetime stress (n = 55), at-risk of mental disorder exposed to the same level of stress (n = 68), and controls (n = 123). Personality was assessed by the NEO-Five Factor Inventory (NEO-FFI). Voxelwise statistics of DTI values in CC were obtained using tract-based spatial statistics. Regional projections were identified by probabilistic tractography.

RESULTS

Higher FA values were detected in the anterior CC of resilient compared to both non-resilient and control adolescents. FA values varied according to resilience capacity. Seed regional changes in anterior CC projected onto anterior cingulate and frontal cortex. Neuroticism and three other NEO-FFI factor scores differentiated non-resilient participants from the other two groups.

CONCLUSION

High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk was associated with personality characteristics. Resilience in adolescence may be related to white-matter microstructure.

Psychiatric consequences of intraoperative awareness: short review and case series

Intraoperative awareness is an unwanted outcome that consists of an explicit recall of events during a surgical procedure performed under general anesthesia. Despite its relatively infrequent occurrence, intraoperative awareness is of significant concern due to frequent adverse psychiatric sequelae. We present three patients who developed posttraumatic sequelae following an episode of awareness under anesthesia and discuss the importance of early detection and specific care.

Resilience and brain connectivity

A definition of resilience is the capacity to resist mental disorders despite exposure to stress. Little is known about its biological concomitants. In adults, biochemical and hormonal factors have been advocated. Smaller Corpus Callosum (CC) volume and lower Fractional Anisotropy (FA) have been observed in psychiatric and stress-related conditions. There is no Diffusion Tensor Imaging (DTI) study of resilience in adolescence, a critical lifetime period for neural and psychological maturation. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents.

Methods

Three community groups were compared: resilient adolescents – with low risk of mental disorder despite high exposure to lifetime stress, adolescents at risk of mental disorder exposed to the same level of stress, and controls. Personality was assessed by NEO Five Factor Inventory (NEO-FFI) and cognitive function by a battery of tests. Voxelwise statistics of DTI values in CC were obtained using Tract-Based Spatial Statistic. Regional projections were identified by probabilistic tractography.

results

Higher FA values were detected in the anterior CC of resilient compared with both non-resilient and control adolescents. FA values varied according to resilience capacity. Regional changes in CC were in regions that project onto anterior cingulated and frontal cortex. Neuroticism and three other personality factors differentiated at risk adolescents from the other two groups.

Conclusion

High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk in adolescents was associated with personality characteristics. Resilience in adolescence may be a dimension embedding white matter features.

Vulnérabilité aux troubles de l’humeur à l’adolescence

L’instabilité émotionnelle est fréquente à l’adolescence et peut parfois être considérée comme un trouble de l’humeur subsyndromique. Or, les tableaux subsyndromiques de manie ou de dépression à l’adolescence évoluent souvent vers des troubles de l’humeur. Nous avons recherché, chez des adolescents « subsyndromiques », s’il existait des modifications cérébrales voisines de celles retrouvées dans les troubles de l’humeur avérés. Les participants étaient tous issus de la cohorte IMAGEN qui a rassemblé des données de plus de 2000 adolescents européens scolarisés en classes de 4e et 3e. Ils avaient été examinés en imagerie cérébrale anatomique (IRM T1 et de diffusion) et évalués par un entretien diagnostique informatisé permettant l’évaluation d’éventuels symptômes. Une première étude a comparé la microstructure de la substance blanche et le volume de substance grise chez des participants présentant des symptômes bipolaires maniaques subsyndromiques comparés à des adolescents pris comme témoins. Une deuxième étude a été menée chez des adolescents ayant des symptômes subsyndromiques de dépression. L’analyse des images a mis en évidence chez les adolescents à bipolarité subsyndromique des variations de la microstructure de la substance blanche dans plusieurs faisceaux en cours de maturation, et un moindre volume de substance grise dans des régions du cerveau contribuant à la régulation émotionnelle. Chez les adolescents « subdéprimés », des modifications étaient également présentes dans le réseau fronto-striatal. Pour la première fois, des modifications de la structure cérébrale de régions impliquées dans les troubles de l’humeur ont été mises en évidence chez des adolescents scolarisés ayant des symptômes subsyndromiques. Ces résultats suggèrent des particularités de maturation cérébrale à l’adolescence qui pourraient entraîner une vulnérabilité aux troubles de l’humeur.