Elevated Amygdala Perfusion Mediates Developmental Sex Differences in Trait Anxiety

BACKGROUND

Adolescence is a critical period for emotional maturation and is a time when clinically significant symptoms of anxiety and depression increase, particularly in females. However, few studies relate developmental differences in symptoms of anxiety and depression to brain development. Cerebral blood flow is one brain phenotype that is known to have marked developmental sex differences.

METHODS

We investigated whether developmental sex differences in cerebral blood flow mediated sex differences in anxiety and depression symptoms by capitalizing on a large sample of 875 youths who completed cross-sectional imaging as part of the Philadelphia Neurodevelopmental Cohort. Perfusion was quantified on a voxelwise basis using arterial spin-labeled magnetic resonance imaging at 3T. Perfusion images were related to trait and state anxiety using general additive models with penalized splines, while controlling for gray matter density on a voxelwise basis. Clusters found to be related to anxiety were evaluated for interactions with age, sex, and puberty.

RESULTS

Trait anxiety was associated with elevated perfusion in a network of regions including the amygdala, anterior insula, and fusiform cortex, even after accounting for prescan state anxiety. Notably, these relationships strengthened with age and the transition through puberty. Moreover, higher trait anxiety in postpubertal females was mediated by elevated perfusion of the left amygdala.

CONCLUSIONS

Taken together, these results demonstrate that differences in the evolution of cerebral perfusion during adolescence may be a critical element of the affective neurobiological characteristics underlying sex differences in anxiety and mood symptoms.

Nicotine withdrawal alters neural responses to psychosocial stress

INTRODUCTION

Psychosocial stress is considered to be an important mechanism underlying smoking behavior and relapse. Thus, understanding the effects of acute nicotine withdrawal on responses to stress is important to intervene to prevent stress-induced relapse. The current study investigated the neural correlates of psychosocial stress during acute nicotine withdrawal in chronic smokers.

METHODS

Thirty-nine treatment-seeking smokers were randomized to one of two conditions (abstinent 24 h (n = 21) or smoking as usual (n = 18)). They were then exposed to the Montreal Imaging Stress Task (MIST), a psychosocial stress task consisting of difficult mental arithmetic problems while receiving negative performance feedback while undergoing functional magnetic resonance imaging (fMRI).

RESULTS

Subjective measures of stress increased following the MIST, compared to baseline. Whole brain between-group analysis identified significant activation clusters in four regions for the stress induction minus control contrast: inferior frontal gyrus (IFG), anterior/para cingulate cortex (ACC), precuneus, and supramarginal gyrus (SMG). In all regions, the deprived group showed significantly greater activation compared to the non-deprived group. No significant correlations were found between subjective stress and BOLD signal activation (ps > 0.07).

CONCLUSIONS

This study provides new evidence that brain regions previously shown to be predictive of relapse, such as the precuneus and IFG, display heightened neural responses to stress during nicotine deprivation. These data identify the brain regions that may be associated with withdrawal-related stress responses. Increased stress-related activation during nicotine withdrawal may identify those most vulnerable to relapse and represent a target for novel pharmacological intervention.

The impact of quality assurance assessment on diffusion tensor imaging outcomes in a large-scale population-based cohort

BACKGROUND

Diffusion tensor imaging (DTI) is applied in investigation of brain biomarkers for neurodevelopmental and neurodegenerative disorders. However, the quality of DTI measurements, like other neuroimaging techniques, is susceptible to several confounding factors (e.g., motion, eddy currents), which have only recently come under scrutiny. These confounds are especially relevant in adolescent samples where data quality may be compromised in ways that confound interpretation of maturation parameters. The current study aims to leverage DTI data from the Philadelphia Neurodevelopmental Cohort (PNC), a sample of 1601 youths with ages of 8-21 who underwent neuroimaging, to: 1) establish quality assurance (QA) metrics for the automatic identification of poor DTI image quality; 2) examine the performance of these QA measures in an external validation sample; 3) document the influence of data quality on developmental patterns of typical DTI metrics.

METHODS

All diffusion-weighted images were acquired on the same scanner. Visual QA was performed on all subjects completing DTI; images were manually categorized as Poor, Good, or Excellent. Four image quality metrics were automatically computed and used to predict manual QA status: Mean voxel intensity outlier count (MEANVOX), Maximum voxel intensity outlier count (MAXVOX), mean relative motion (MOTION) and temporal signal-to-noise ratio (TSNR). Classification accuracy for each metric was calculated as the area under the receiver-operating characteristic curve (AUC). A threshold was generated for each measure that best differentiated visual QA status and applied in a validation sample. The effects of data quality on sensitivity to expected age effects in this developmental sample were then investigated using the traditional MRI diffusion metrics: fractional anisotropy (FA) and mean diffusivity (MD). Finally, our method of QA is compared with DTIPrep.

RESULTS

TSNR (AUC=0.94) best differentiated Poor data from Good and Excellent data. MAXVOX (AUC=0.88) best differentiated Good from Excellent DTI data. At the optimal threshold, 88% of Poor data and 91% Good/Excellent data were correctly identified. Use of these thresholds on a validation dataset (n=374) indicated high accuracy. In the validation sample 83% of Poor data and 94% of Excellent data was identified using thresholds derived from the training sample. Both FA and MD were affected by the inclusion of poor data in an analysis of an age, sex and race matched comparison sample. In addition, we show that the inclusion of poor data results in significant attenuation of the correlation between diffusion metrics (FA and MD) and age during a critical neurodevelopmental period. We find higher correspondence between our QA method and DTIPrep for Poor data, but we find our method to be more robust for apparently high-quality images.

CONCLUSION

Automated QA of DTI can facilitate large-scale, high-throughput quality assurance by reliably identifying both scanner and subject induced imaging artifacts. The results present a practical example of the confounding effects of artifacts on DTI analysis in a large population-based sample, and suggest that estimates of data quality should not only be reported but also accounted for in data analysis, especially in studies of development.

The Philadelphia Neurodevelopmental Cohort: A publicly available resource for the study of normal and abnormal brain development in youth

The Philadelphia Neurodevelopmental Cohort (PNC) is a large-scale study of child development that combines neuroimaging, diverse clinical and cognitive phenotypes, and genomics. Data from this rich resource is now publicly available through the Database of Genotypes and Phenotypes (dbGaP). Here we focus on the data from the PNC that is available through dbGaP and describe how users can access this data, which is evolving to be a significant resource for the broader neuroscience community for studies of normal and abnormal neurodevelopment.

Neuroimaging of the Philadelphia neurodevelopmental cohort

The Philadelphia Neurodevelopmental Cohort (PNC) is a large-scale, NIMH funded initiative to understand how brain maturation mediates cognitive development and vulnerability to psychiatric illness, and understand how genetics impacts this process. As part of this study, 1445 adolescents ages 8-21 at enrollment underwent multimodal neuroimaging. Here, we highlight the conceptual basis for the effort, the study design, and the measures available in the dataset. We focus on neuroimaging measures obtained, including T1-weighted structural neuroimaging, diffusion tensor imaging, perfusion neuroimaging using arterial spin labeling, functional imaging tasks of working memory and emotion identification, and resting state imaging of functional connectivity. Furthermore, we provide characteristics regarding the final sample acquired. Finally, we describe mechanisms in place for data sharing that will allow the PNC to become a freely available public resource to advance our understanding of normal and pathological brain development.

Enhanced efficacy of oral sotalol for sustained ventricular tachycardia refractory to type I antiarrhythmic drugs

Sotalol is a nonselective beta-adrenergic blocking agent with Vaughn-Williams class III activity. Its efficacy was tested in 9 patients with sustained ventricular tachycardia (VT) that had previously remained inducible during electrophysiologic testing of type I drugs (procainamide or quinidine). Eight patients had coronary artery disease with remote myocardial infarction and 1 had cardiomyopathy (ejection fraction 0.34 +/- 0.08, mean +/- standard deviation). Type I drugs prolonged the effective refractory period of the right ventricle 12 +/- 14% and prolonged the VT cycle length 41 +/- 24%. In contrast, despite an equivalent effect on the effective refractory period, a sustained VT could no longer be initiated in any of the 8 patients ultimately tested while taking oral sotalol. Daily doses averaged 600 +/- 103 mg and blood levels associated with VT suppression in electrophysiologic studies were generally greater than 3,000 ng/ml. In addition, sotalol was moderately effective at reducing ventricular ectopic activity measured by ambulatory electrocardiography. Over a mean follow-up of 23 months (range 1 to 37), mild heart failure (3 patients), symptomatic brady-cardia requiring pacemaker (1) and drug-related polymorphous VT (1) have occurred. Sudden death occurred in 1 patient and nonfatal VT recurrence was noted in 2. Five of 8 chronically treated patients currently are successfully treated with minimal side effects. Sotalol appears to be a promising antiarrhythmic drug in the treatment of serious ventricular arrhythmias, even in patients refractory to type I antiarrhythmic agents.

Energy, current, and success in defibrillation and cardioversion: clinical studies using an automated impedance-based method of energy adjustment

The purposes of this study were two. First, we wanted to evaluate in patients a technique for automated adjustment of selected energy for defibrillation or cardioversion based on transthoracic impedance. Second, we wanted to define the relationship of peak current and shock success in various arrhythmias. Applying a previously validated method of predicting transthoracic impedance in advance of any shock, we modified defibrillators to automatically double the operator-selected energy if the predicted impedance exceeded 70 omega. Success rates of shocks given for ventricular and atrial arrhythmias from these modified energy-adjusting defibrillators were compared with success rates for shocks given from standard defibrillators. We prospectively collected data on 347 patients who received a total of 1009 shocks. Low-energy (100 J) shocks given to high-impedance (greater than or equal to 70 omega) patients had a poor success rate; in such high-impedance patients significant improvement in shock success rate was achieved by the energy-adjusting defibrillators. For example, when 100 J shocks were selected for high-impedance patients in ventricular fibrillation the energy-adjusting defibrillators achieved a shock success rate of 75%, whereas standard defibrillators achieved a shock success rate of only 36% (p less than .01). Similar improvements were seen for ventricular tachycardia and atrial fibrillation. Thus, automated energy adjustment based on transthoracic impedance is a beneficial approach to defibrillation and cardioversion. For ventricular fibrillation, atrial fibrillation, and atrial flutter there was a clear relationship between peak current and shock success.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival in childhood acute lymphocytic leukemia: effect of protocol and place of treatment

The objective of this study was to determine the effect of place and type of initial treatment on survival from acute lymphocytic leukemia (ALL). Every one of the 327 children under 15 years of age diagnosed with ALL from 1970 to 1975 in a 31-county area designated the Greater Delaware Valley, were studied. Treatment according to protocol was associated with improved survival, yielding a 4 year survival of 60% vs 19% for nonprotocol treated patients (p less than 0.001). There was also a significantly improved survival rate among patients treated in a cancer center, especially for those with a low white blood count (WBC) at diagnosis. The prognostic importance of WBC, age, and sex was confirmed.

Breast cancer without axillary metastases. Are there high-risk biologic subpopulations?

Two hundred seventy-five patients with breast cancer and no axillary metastases had mastectomies and axillary node dissection performed during the period between 1970 and 1979 at The Fox Chase Cancer Center. They had a mean age of 60 years (range, 21-91) and 38 (14%) patients have had recurrence to date. Poor histologic differentiation and skin involvement were related to a high risk of recurrence. Those patients with skin infiltration by tumor or a poorly differentiated tumor had a 53 +/- 9% expected five-year tumor-free survival, whereas patients without these had a 90 +/- 2% expected five-year tumor-free survival. Tumor involvement of the lymphatic vessels within the breast and estrogen receptor protein positivity or negativity were not helpful for identifying a subpopulation at increased risk of recurrence. Large tumor size was not a poor prognostic indicator for a patient subpopulation. These factors should be considered as indicators for inclusion in clinical trials and adjuvant therapy and used as stratification points for the analysis of the data developed in these trials.

Analysis of staging and management of patients with sarcoma: a ten-year experience

Over ten years, 70 patients with soft tissue sarcoma were treated for their primary tumors at the hospital of The Fox Chase Cancer Center. The clinical characteristics of these tumors are correlated with the outcome of various management efforts. The results of these evaluations identify three groups that can provide the basis for future treatment decisions and stratification for randomized studies of management options. The first group of patients, those with small well differentiated tumors, have no systemic spread regardless of the treatment modality used. The second group, those with large (greater than 5 cm) tumors that are moderately or poorly differentiated, do uniformly poorly despite the management techniques used. An intermediate group, those with high grade or large size but not both, have outcomes which may be correlated to treatment modalities.