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.

Common structural correlates of trait impulsiveness and perceptual reasoning in adolescence

BACKGROUND

Trait impulsiveness is a potential factor that predicts both substance use and certain psychiatric disorders. This study investigates whether there are common structural cerebral correlates of trait impulsiveness and cognitive functioning in a large sample of healthy adolescents from the IMAGEN project.

METHODS

Clusters of gray matter (GM) volume associated with trait impulsiveness, Cloningers' revised temperament, and character inventory impulsiveness (TCI-R-I) were identified in a whole brain analysis using optimized voxel-based morphometry in 115 healthy 14-year-olds. The clusters were tested for correlations with performance on the nonverbal tests (Block Design, BD; Matrix Reasoning, MT) of the Wechsler Scale of Intelligence for Children IV reflecting perceptual reasoning.

RESULTS

Cloningers' impulsiveness (TCI-R-I) score was significantly inversely associated with GM volume in left orbitofrontal cortex (OFC). Frontal clusters found were positively correlated with performance in perceptual reasoning tasks (Bonferroni corrected). No significant correlations between TCI-R-I and perceptual reasoning were observed.

CONCLUSIONS

The neural correlate of trait impulsiveness in the OFC matches an area where brain function has previously been related to inhibitory control. Additionally, orbitofrontal GM volume was associated with scores for perceptual reasoning. The data show for the first time structural correlates of both cognitive functioning and impulsiveness in healthy adolescent subjects.

[Hypercapnia and mixed acidosis as the only sign of malignant hyperthermia (MH)?]

CASE REPORT

A 34-year-old male (190 cm/100 kg) was scheduled for surgery of the nasal septum. He had had uneventful anaesthesia for appendicectomy 14 years earlier: following 600 mg thiopentone, 180 mg suxamethonium and up to 2 vol.% halothane for 20 min had been used and no symptoms of malignant hyperthermia (MH) were recorded. Following oral premedication with 2 mg flunitrazepam at 7.00 a.m. anaesthesia was induced with a priming dose of atracurium at 8.45 a.m. followed by 0.2 mg fentanyl, 500 mg thiopentone, and 100 mg suxamethonium. Endotracheal intubation was accomplished easily, and the patient was ventilated manually in a semi-closed circle system until spontaneous ventilation resumed. Enflurane (1.5% for 5 min, 1.0% for 10 min, and 0.8% until the diagnosis of MH was suspected) was given in 33% O2/66% N2O. Seventy minutes after induction it was noted that the spontaneous respiratory rate and minute volume had risen continuously from 10/min and 6 l/min, respectively, to 20/min and 12 l/min. Attempts at deepening anaesthesia with repeated doses of fentanyl up to a total dose of 0.95 mg failed to reduce the hyperventilation. In spite of a high fresh gas flow of 6 l/min and assisted manual ventilation, the FIO2 started to fall from 0.34 to 0.28 at 10:20 a.m. The O2/N2O ratio was changed to 1:1, but the FIO2 remained at 0.3. MH was suspected, enflurane was discontinued, and an arterial blood gas analysis was done (Table 2). When marked acidosis and hypercarbia were found, dantrolene 2.5 mg/kg was given, the operation was terminated, and the patient's trachea was extubated and he was monitored closely in the intensive care unit for 24 h. Vital signs were stable (Table 3) and no further complications were observed. The patient did not mention pain or uneasiness postoperatively. About 6 months later, a muscle biopsy was done according to the European MH Protocol and the patient was found to be MHEh.

DISCUSSION

In this case five main reasons for the hypercarbia and mixed acidosis must be considered (Table 1). Firstly, hypoventilation does not seem to be reasonable as the patient was ventilated with 8 to 12 l/min, which is within the range of 80-120 ml/kg.min. Secondly, we can exclude shock and hypoperfusion because the patient had a normal blood pressure and heart rate (within 65-90 beats/min), his fingertips and skin were well perfused, his body temperature was 37 degrees C, and there was no sign of muscle rigidity. Thirdly, a defect of the CO2 absorber as well as CO2 admixture to the N2O and O2 ventilation gases can cause hypercarbia. We use two absorbers in sequence of which one is changed every day, and found neither a change in colour of the indicator nor an abnormally raised temperature of the absorbers. A postoperative check of the ventilator showed no defect in the O2/N2O supply and a correctly functioning anaesthesia apparatus. A malfunction of both CO2 absorbers resulting in intraoperative hypercarbia could not explain a postoperative mixed acidosis lasting for more than 6 h. Anaesthesias performed at the same time using soda lime from the same canisters were totally uneventful.

CONCLUSION

It is concluded that the hypercarbia and mixed acidosis were caused by hypermetabolism. A thorough postoperative examination by an internist did not reveal any thyroid, pulmonary, endocrine, or circulatory reason for our intra- and postoperative findings. Iatrogenic factors like superficial anaesthesia or systemic side effects of adrenaline admixture to local anaesthetics can cause hypermetabolism without striking clinical signs, but they do not cause mixed acidosis lasting longer than 6 h (Table 2). The most suitable explanation in this case is an abortive form of MH. Even patients who are MHS positive on muscle biopsy do not necessarily go through an MH crisis every time they have stress or undergo anaesthesia. The diagnosis of a fulminant MH crisis is a clinical one. Therefore, we are aware that there is no direct scientific ev

[Oleic acid-induced interstitial lung edema in the dog: comparison of PEEP with high-frequency jet superimposed ZEEP ventilation]

Oleic acid (0.12 ml/kg) was used to induce pulmonary edema in 10 mongrel dogs. To treat the consequent hypoxaemia we used either positive end expiratory pressure (PEEP) ventilation (n = 5) or zero end expiratory pressure ventilation (ZEEP) plus additional high frequency jet support (n = 5). Hypoxaemia, which paralleled the dramatic increase in lung water, was significantly improved (aADO2) by PEEP but not by ZEEP plus jet. Also venous admixture was significantly lowered by PEEP only. Cardiac output and pulmonary arterial pressure in the two groups were not significantly different. This demonstrates that ZEEP plus jet is not superior to PEEP in the case of oleic acid induced edema, though we obtained good clinical results with the former system in the treatment of atelectasis. In addition, histological evaluation of the dog lungs showed emphysematous lung injury by the jet system, which indicates that such a jet system should be used with caution.

[Choice of anaesthesia technique in thoracic endoscopic sympathectomy (author's transl)]

Thoracic endoscopic sympathectomy (TES) is a short surgical procedure used for the treatment of palmar and axillary hyperhidrosis. It involves pneumothorax, the lateral and head up position, and necessitates minimal chest excursions during breathing, so that a special type of anaesthesia is required. In 13 patients two different methods were compared and blood gas analysis as well as circulatory parameters were studied. We therefore propose an anaesthetic method using controlled mechanical ventilation; relaxation; intravenous anaesthesia; at least 1 1 fluid replacement; and careful monitoring.

[Acute poisoning with tricylic antidepressants and treatment with physostigmine salicylate (author's transl)]

Three cases of self poisoning with tricyclic antidepressants (TAD) are reported, one of them with a potentially lethal dose. All three cases were treated with physostigmine salicylate (PS) and in two cases there was complete reversal of coma within a few minutes. In striking contrast to the reported high incidence of cardiac arrhythmias no cardiac complications were observed in any of the cases. Therefore we think that the use of PS should be considered when treating cases of TAD poisoning.

[Severe accidental acrolein intoxication in the home (author's transl)]

In a private household overheated fat-containing food emitted vapours which caused severe intoxication in a previously healthy man. The resulting pulmonary changes presented a grave threat to the patient's life for several days. The origin and properties of the vapours led to the conclusion that acrolein was their major toxic component.