The neurodevelopmental frontostriatal disorders: evolutionary adaptiveness and anomalous lateralization

The promise of precision functional mapping for neuroimaging in psychiatry

Precision functional mapping (PFM) is a neuroimaging approach to reliably estimate metrics of brain function from individual people via the collection of large amounts of fMRI data (hours per person). This method has revealed much about the inter-individual variation of functional brain networks. While standard group-level studies, in which we average brain measures across groups of people, are important in understanding the generalizable neural underpinnings of neuropsychiatric disorders, many disorders are heterogeneous in nature. This heterogeneity often complicates clinical care, leading to patient uncertainty when considering prognosis or treatment options. We posit that PFM methods may help streamline clinical care in the future, fast-tracking the choice of personalized treatment that is most compatible with the individual. In this review, we provide a history of PFM studies, foundational results highlighting the benefits of PFM methods in the pursuit of an advanced understanding of individual differences in functional network organization, and possible avenues where PFM can contribute to clinical translation of neuroimaging research results in the way of personalized treatment in psychiatry.

Leveling Up Dialectical Behavior Therapy for Autistic Individuals with Emotion Dysregulation: Clinical and Personal Insights

Autistic people may experience high emotion and sensory sensitivities and a slow return to baseline emotional state. Dialectical behavior therapy (DBT) was developed to address reactivity, impulsivity, and mood dysregulation in individuals with mood and personality disorders. DBT may be therapeutically beneficial to autistic individuals struggling with these or similar emotional and sensory challenges. This article is a synthesis of the first author's experiences of DBT as an autistic person and professional insights from all authors. We provide an overview of the development of DBT, its foundational components, and adaptations. Using this basis, the first author describes the benefits DBT has had, the modifications that have helped him, and how those modifications may enhance DBT for autistic people. Modifications include visuals, graphics, and a gaming format that target the client's personal interests. The essence of these alterations is to transform life skills and DBT skills into something meaningful and functional. Receptivity of the therapist to the modifications and neurodivergent problem solving may be foundational to therapeutic success. Client-initiated contributions in collaborative therapy may improve autistic participants' understanding, validation, and adherence with DBT. The authors suggest expanding work on DBT modifications for autism in the areas of daily self-monitoring, assessing for preferred visual and gaming formats, and utilizing personal interests.

Evaluation of Autism Spectrum Disorder Risk in Infants With Intraventricular Hemorrhage

Background This study evaluates the long-term risk of autism spectrum disorder (ASD) in infants with intraventricular hemorrhage (IVH) using the Modified Checklist for Autism in Toddlers-Revised with Follow-Up (M-CHAT-R/F) screening tool. Methods This retrospective cohort study compared IVH (exposed) infants across all gestational age groups with no-IVH (non-exposed) infants admitted to level IV neonatal intensive care unit (NICU). The M-CHAT-R/F screening tool was used to assess the ASD risk at 16-30 months of age. Discharge cranial ultrasound (CUS) findings also determined the ASD risk. Descriptive statistics comprised median and interquartile range for skewed continuous data and frequencies and percentages for categorical variables. Comparisons for non-ordinal categorical measures in bivariate analysis were carried out using the χ2 test or Fisher exact test. Results Of the 334 infants, 167 had IVH, and 167 had no IVH. High ASD risk (43% vs. 20%, p = 0.044) and cerebral palsy (19% vs. 5%, p = 0.004) were significantly associated with severe IVH. Infants with CUS findings of periventricular leukomalacia had 3.24 odds of developing high ASD risk (odds ratios/OR: 3.24, 95% confidence interval/CI: 0.73-14.34), and those with hydrocephalus needing ventriculoperitoneal (VP) shunt had 4.75 odds of developing high ASD risk (OR: 4.75, 95% CI: 0.73-30.69). Conclusion Severe IVH, but not mild IVH, increased the risk of ASD and cerebral palsy. This study demonstrates the need for timely screening for ASD in high-risk infants. Prompt detection leads to earlier treatment and better outcomes.

Thalamo-cortical and cerebello-cortical functional connectivity in development

The thalamus is a critical relay center for neural pathways involving sensory, motor, and cognitive functions, including cortico-striato-thalamo-cortical and cortico-ponto-cerebello-thalamo-cortical loops. Despite the importance of these circuits, their development has been understudied. One way to investigate these pathways in human development in vivo is with functional connectivity MRI, yet few studies have examined thalamo-cortical and cerebello-cortical functional connectivity in development. Here, we used resting-state functional connectivity to measure functional connectivity in the thalamus and cerebellum with previously defined cortical functional networks in 2 separate data sets of children (7-12 years old) and adults (19-40 years old). In both data sets, we found stronger functional connectivity between the ventral thalamus and the somatomotor face cortical functional network in children compared with adults, extending previous cortico-striatal functional connectivity findings. In addition, there was more cortical network integration (i.e. strongest functional connectivity with multiple networks) in the thalamus in children than in adults. We found no developmental differences in cerebello-cortical functional connectivity. Together, these results suggest different maturation patterns in cortico-striato-thalamo-cortical and cortico-ponto-cerebellar-thalamo-cortical pathways.

Cingulate sulcus morphology and paracingulate sulcus variations: Anatomical and radiological studies

The sulci and gyri found across the cerebrum differ in morphology between individuals. The cingulate sulcus is an important landmark for deciding the surgical approach for neighboring pathological lesions. Identifying the anatomical variations of anterior cingulate cortex morphology would help to determine the safe-entry route through neighboring lesions. In this study, magnetic resonance imaging data acquired from 149 healthy volunteers were investigated retrospectively for anatomical variations of the paracingulate sulcus. Also, human cadaveric brain hemispheres were investigated for cingulate and paracingulate sulcus anatomy. All participants had cingulate sulci in both hemispheres (n = 149, 100%). Three types of paracingulate sulcus patterns were identified: "prominent," "present," and "absent." Hemispheric comparisons indicated that the paracingulate sulcus is commonly "prominent" in the left hemisphere (n = 48, 32.21%) and more commonly "absent" in the right hemisphere (n = 73, 48.99%). Ten (6.71%) people had a prominent paracingulate sulcus in both the right and left hemispheres. Seven (4.70%) of them were male, and 3 (2.01%) of them were female. Paracingulate sulci were present in both hemispheres in 19 people (12.75%), of which 9 (6.04%) were male and 10 (6.71%) were female. There were 35 (23.49%) participants without paracingulate sulci in both hemispheres. Eleven (7.38%) were male and 24 (16.11%) were female. There were 73 (48.99%) participants without right paracingulate sulcus and 57 (38.26%) participants without left paracingulate sulcus (p = 0.019). In the examinations of the cadaver hemispheres, the paracingulate sulcus was present and prominent in 25%, and the intralimbic sulcus was present in 15%. It has been observed that the paracingulate sulcus is more prominent in the normal male brain compared to females. In females, there were more participants without paracingulate sulcus. This study shows that there are both hemispheric and sex differences in the anatomy of the paracingulate sulcus. Understanding the cingulate sulcus anatomy and considering the variations in the anterior cingulate cortex morphology during surgery will help surgeons to orient this elegant and complex area.

Laterality Hotspots in the Striatum

Striatal loci are connected to both the ipsilateral and contralateral frontal cortex. Normative quantitation of the dissimilarity between striatal loci's hemispheric connection profiles and its spatial variance across the striatum, and assessment of how interindividual differences relate to function, stands to further the understanding of the role of corticostriatal circuits in lateralized functions and the role of abnormal corticostriatal laterality in neurodevelopmental and other neuropsychiatric disorders. A resting-state functional connectivity fingerprinting approach (n = 261) identified "laterality hotspots"-loci whose profiles of connectivity with ipsilateral and contralateral frontal cortex were disproportionately dissimilar-in the right rostral ventral putamen, left rostral central caudate, and bilateral caudal ventral caudate. Findings were replicated in an independent sample and were robust to both preprocessing choices and the choice of cortical atlas used for parcellation definitions. Across subjects, greater rightward connectional laterality at the right ventral putamen hotspot and greater leftward connectional laterality at the left rostral caudate hotspot were associated with higher performance on tasks engaging lateralized functions (i.e., response inhibition and language, respectively). In sum, we find robust and reproducible evidence for striatal loci with disproportionately lateralized connectivity profiles where interindividual differences in laterality magnitude are associated with behavioral capacities on lateralized functions.

Precision Functional Mapping of the Subcortex and Cerebellum

Human functional brain networks can be reliably characterized within individuals using precision functional mapping. This approach entails the collection of large quantities of functional magnetic resonance imaging (fMRI) data from each individual subject. Studies employing precision functional mapping in the cerebral cortex have found that individuals manifest unique representations of functional brain networks around a central tendency described by previous group average approaches. We recently extended precision functional mapping to the subcortex and cerebellum, which has revealed several novel organizational principles within these structures. Here, we detail these principles and provide insights into how precision functional mapping of subcortical structures and the cerebellum may become clinically translatable.

Defining Individual-Specific Functional Neuroanatomy for Precision Psychiatry

Studies comparing diverse groups have shown that many psychiatric diseases involve disruptions across distributed large-scale networks of the brain. There is hope that functional magnetic resonance imaging (fMRI) functional connectivity techniques will shed light on these disruptions, providing prognostic and diagnostic biomarkers as well as targets for therapeutic interventions. However, to date, progress on clinical translation of fMRI methods has been limited. Here, we argue that this limited translation is driven by a combination of intersubject heterogeneity and the relatively low reliability of standard fMRI techniques at the individual level. We review a potential solution to these limitations: the use of new "precision" fMRI approaches that shift the focus of analysis from groups to single individuals through the use of extended data acquisition strategies. We begin by discussing the potential advantages of fMRI functional connectivity methods for improving our understanding of functional neuroanatomy and disruptions in psychiatric disorders. We then discuss the budding field of precision fMRI and findings garnered from this work. We demonstrate that precision fMRI can improve the reliability of functional connectivity measures, while showing high stability and sensitivity to individual differences. We close by discussing the application of these approaches to clinical settings.

Lateralization of attention in adults with ADHD: Evidence of pseudoneglect

Background.

We investigated whether adults with attention-deficit/hyperactivity disorder (ADHD) show pseudoneglect—preferential allocation of attention to the left visual field (LVF) and a resulting slowing of mean reaction times (MRTs) in the right visual field (RVF), characteristic of neurotypical (NT) individuals —and whether lateralization of attention is modulated by presentation speed and incentives.

Method.

Fast Task, a four-choice reaction-time task where stimuli were presented in LVF or RVF, was used to investigate differences in MRT and reaction time variability (RTV) in adults with ADHD (n = 43) and NT adults (n = 46) between a slow/no-incentive and fast/incentive condition. In the lateralization analyses, pseudoneglect was assessed based on MRT, which was calculated separately for the LVF and RVF for each condition and each study participant.

Results.

Adults with ADHD had overall slower MRT and increased RTV relative to NT. MRT and RTV improved under the fast/incentive condition. Both groups showed RVF-slowing with no between-group or between-conditions differences in RVF-slowing.

Conclusion.

Adults with ADHD exhibited pseudoneglect, a NT pattern of lateralization of attention, which was not attenuated by presentation speed and incentives.

Striatal dynamics as determinants of reduced gambling vulnerability in the NHE rat model of ADHD

The Naples High-Excitability (NHE) is a validated rat strain to model for a mesocortical variant of Attention Deficit Hyperactivity Disorder (ADHD). NHE rats' brains have a tuned-down cortical and a potentiated limbic loop (Zoratto et al., 2017). ADHD and comorbid pathological gambling (PG) involve similar deficits of prefrontal-striatal dialogue. This work aimed to understand if NHE rats (compared to normal random-bred rats, NRB) can be a useful model for gambling vulnerability in ADHD. Experiment 1 evaluated gambling proneness in NHE rats, namely attraction/avoidance in nose-poking for a "Large & Luck-Linked" (LLL) reward (versus a "Small & Sure" one, SS), when the probability of LLL delivery was progressively reduced. Experiment 2 assessed (by phMRI) differential responsivity of ventral (vStr) versus dorsal (dStr) striatum following a methylphenidate (MPH, 4 mg/kg I.P.) challenge. In NHE rats, reduced attraction by secondary cues (associated with uncertain, rarefying LLL delivery) comes along with little or no activation of dStr and enhanced activation of vStr by MPH. Together, such evidences from NHE rats indicate distinctive roles of ventral (enhanced value given to actual primary reward) and dorsal (lower encoding of repeated stimulus-reward associations into a habit) striatum. In conclusion, the dynamics of reward systems could link an attention deficit with a decreased vulnerability to pathological gambling.

Integrative and Network-Specific Connectivity of the Basal Ganglia and Thalamus Defined in Individuals

The basal ganglia, thalamus, and cerebral cortex form an interconnected network implicated in many neurological and psychiatric illnesses. A better understanding of cortico-subcortical circuits in individuals will aid in development of personalized treatments. Using precision functional mapping-individual-specific analysis of highly sampled human participants-we investigated individual-specific functional connectivity between subcortical structures and cortical functional networks. This approach revealed distinct subcortical zones of network specificity and multi-network integration. Integration zones were systematic, with convergence of cingulo-opercular control and somatomotor networks in the ventral intermediate thalamus (motor integration zones), dorsal attention and visual networks in the pulvinar, and default mode and multiple control networks in the caudate nucleus. The motor integration zones were present in every individual and correspond to consistently successful sites of deep brain stimulation (DBS; essential tremor). Individually variable subcortical zones correspond to DBS sites with less consistent treatment effects, highlighting the importance of PFM for neurosurgery, neurology, and psychiatry.

A transdiagnostic model of psychiatric symptom co-occurrence and autism spectrum disorder

Understanding whether the co-occurrence of psychiatric symptoms within autism spectrum disorder (ASD) are specific to the ASD diagnosis or reflect similar higher-order patterns observed in both ASD and non-ASD samples, or a confluence of the two, is of critical importance. If similar, it would suggest that comorbid psychiatric conditions among individuals with ASD are not symptoms of specific, non-ASD psychiatric disorders per se, but reflect a general liability to psychopathology associated with ASD. To this end, the current study examined whether the higher-order structure of co-occurring psychiatric symptoms was the same within ASD and non-ASD youth. Parents of clinic-referred youth with (n = 280) and without (n = 943) ASD completed a DSM-IV-referenced psychiatric symptom rating scale. A confirmatory factor analytic framework was used to examine four levels of measurement invariance across groups to determine the extent to which transdiagnostic factors were comparable. Transdiagnostic factors were characterized by symptoms of the same disorders (configural invariance) and the same factor loadings across groups (metric invariance). Furthermore, both groups evidenced equivalent numbers of symptoms of most psychiatric conditions with the notable exceptions of attention deficit hyperactivity disorder (ADHD) and social anxiety (partial strong invariance), which were higher in the ASD sample. It was concluded that disparities in the co-occurrence of psychiatric symptoms between youth with and without ASD may be largely reflective of transdiagnostic factor level differences associated with ASD and not indicative of the ASD diagnosis per se. However, for ADHD and social anxiety, there appears to be some specific associations with the ASD diagnosis. Autism Res 2020, 13: 579-590. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Few transdiagnostic dimensions relate common mental disorder diagnoses with one another. These dimensions explain psychiatric comorbidity (i.e., the finding that many persons possess several disorder diagnoses simultaneously). However, it is unclear if these dimensions differ among children with autism spectrum disorder (ASD), compared with their non-ASD counterparts. The results of this study demonstrate that underlying transdiagnostic dimensions are similar in both ASD and non-ASD children. However, there appear to be ASD-specific differences when it comes to social anxiety and attention deficit hyperactivity disorder.

Variations of cingulate sulcal organization and link with cognitive performance

The sulcal morphology of the human medial frontal cortex has received marked interest because of (1) its remarkable link with the functional organization of this region, and (2) observations that deviations from 'normal' sulcal morphological variability correlate with the prevalence of some psychiatric disorders, cognitive abilities, or personality traits. Unfortunately, background studies on environmental or genetic factors influencing the ontogenesis of the sulcal organization in this region are critically lacking. We analysed the sulcal morphological organization in this region in twins and non-twin siblings, as well as in control subjects for a total of 599 subjects from the Human Connectome Project. The data first confirm significant biases in the presence of paracingulate sulci in left vs right hemispheres in the whole population (twin: p < 2.4.10-9; non-twin: p < 2.10-6) demonstrating a clear general laterality in human subjects. Second, measures of similarity between siblings and estimations of heritability suggest significant environmental factors, in particular in-womb environment, and weak additive genetic factors influencing the presence of a paracingulate sulcus. Finally, we found that relationships between sulcal organization and performance in cognitive, motor, and affective tests depend on the twin status (Twins versus Non-twins). These results provide important new insights to the issue of the significance of sulcal organization in the human medial frontal cortex.

Prenatal exposure to disaster-related traumatic stress and developmental trajectories of temperament in early childhood: Superstorm Sandy pregnancy study

BACKGROUND

Little is known about the impact of prenatal maternal stress (PNMS) on the developmental trajectory of temperament and few studies have been able to incorporate a natural disaster as a quasi-experimental stressor. The current study investigated PNMS related to Superstorm Sandy ('Sandy'), a hurricane that struck the New York metropolitan area in October 2012, in terms of objective exposure during pregnancy, subjective stress reaction as assessed by maternal symptoms of post-traumatic stress, and their impact on the developmental changes in temperament during early childhood.

METHOD

A subsample of 318 mother-child dyads was drawn from the Stress in Pregnancy Study. Temperament was measured at 6, 12, 18, and 24 months of age.

RESULTS

Objective exposure was associated with greater High-Intensity Pleasure, Approach, Perceptual Sensitivity and Fearfulness, but lower Cuddliness and Duration of Orientation at 6 months. Objective exposure and its interaction with subjective stress reaction predicted developmental changes in temperament. In particular, objective exposure was linked to greater increases in Activity Level but decreases in High-Intensity Pleasure, Approach, and Fearfulness. The combination of objective exposure and subjective stress reaction was also associated with greater increases in Activity Level.

LIMITATIONS

Temperament was measured solely via maternal report. Trimester-specific effects of Sandy on temperament were not examined.

CONCLUSION

This is the first study to examine the effects of prenatal maternal exposure to a natural disaster on trajectories of early childhood temperament. Findings suggest that both objective stress exposure and subjective stress reaction in-utero predict developmental trajectories of temperament in early childhood.

Minor Neurological Dysfunctions (MNDs) in Autistic Children without Intellectual Disability

Background: Children with autism spectrum disorder (ASD) require neurological evaluation to detect sensory-motor impairment. This will improve understanding of brain function in children with ASD, in terms of minor neurological dysfunctions (MNDs). Methods: We compared 32 ASD children without intellectual disability (IQ ≥ 70) with 32 healthy controls. A standardized and age-specific neurological examination according to Touwen was used to detect the presence of MNDs. Particular attention was paid to severity and type of MNDs. Results: Children with ASD had significantly higher rates of MNDs compared to controls (96.9% versus 15.6%): 81.3% had simple MNDs (p < 0.0001) and 15.6% had complex MNDs (p = 0.053). The prevalence of MNDs in the ASD group was significantly higher (p < 0.0001) than controls. With respect to specific types of MNDs, children with ASD showed a wide range of fine manipulative disability, sensory deficits and choreiform dyskinesia. We also found an excess of associated movements and anomalies in coordination and balance. Conclusions: Results replicate previous findings which found delays in sensory-motor behavior in ASD pointing towards a role for prenatal, natal and neonatal risk factors in the neurodevelopmental theory of autism.

Relationship Between Executive Functioning and Symptoms of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder in 6-8 Year Old Children

This study examined relationships between executive functioning (EF) and ADHD/ASD symptoms in 339 6-8 year-old children to characterise EF profiles associated with ADHD and ADHD + ASD. ADHD status was assessed using screening surveys and diagnostic interviews. ASD symptoms were measured using the Social Communication Questionnaire, and children completed assessments of EF. We found the EF profile of children with ADHD + ASD did not differ from ADHD-alone and that lower-order cognitive skills contributed significantly to EF. Dimensionally, ASD and inattention symptoms were differentially associated with EF, whereas hyperactivity symptoms were unrelated to EF. Differences between categorical and dimensional findings suggest it is important to use both diagnostic and symptom based approaches in clinical settings when assessing these children's functional abilities.

Frontal alpha asymmetry predicts inhibitory processing in youth with attention deficit/hyperactivity disorder

INTRODUCTION

Atypical asymmetry in brain activity has been implicated in the behavioral and attentional dysregulation observed in ADHD. Specifically, asymmetry in neural activity in the right versus left frontal regions has been linked to ADHD, as well as to symptoms often associated with ADHD such as heightened approach behaviors, impulsivity and difficulties with inhibition. Clarifying the role of frontal asymmetry in ADHD-like traits, such as disinhibition, may provide information on the neurophysiological processes underlying these behaviors.

METHOD

ADHD youth (ADHD: n = 25) and healthy, typically developing controls (TD: n = 25) underwent an electroencephalography (EEG) recording while completing a go/no-go task-a commonly used test measuring behavioral inhibition. In addition, advanced signal processing for source localization estimated the location of signal generators underlying frontal alpha asymmetry (FA) during correct and incorrect trials.

RESULTS

This is the first study in ADHD to demonstrate that the dorsal-lateral prefrontal cortex (DLPFC) may be responsible for generating frontal alpha. During failed inhibition trials, ADHD youth displayed greater FA than TD youth. In addition, within the ADHD group, frontal asymmetry during later processing stages (i.e., 400-800ms after stimulus) predicted a higher number of commission errors throughout the task.

CONCLUSIONS

These results suggest that frontal alpha asymmetry may be a specific biomarker of cognitive disinhibition among youth with ADHD.

Hypogyrification in obsessive-compulsive disorder

BACKGROUND

Previous studies hypothesized that neurodevelopmental risk factors may play a role in the pathogenesis of obsessive-compulsive disorder (OCD). Cortical folding has been shown to be a reliable indicator for normal and altered neurodevelopment, but in OCD it has barely been investigated up to now. The present study investigates whether alterations in gyrification are detectable in OCD and, if so, how these are associated with clinical characteristics.

METHOD

We compared the local Gyrification Index (lGI) between 75 OCD patients and 75 matched healthy subjects across the whole brain. In addition, for those regions exhibiting an altered lGI in patients we explored a potential relationship to symptom severity, age of onset, and influence of medication.

RESULTS

OCD patients had a significantly decreased lGI in right parietal, precentral but also insula, temporal, pars triangularis and rostral middle frontal regions compared to healthy subjects. A positive association with age of onset was found but no association with symptom severity. There was no effect of co-morbidity or medication.

CONCLUSIONS

The reduced gyrification found in OCD confirms previous findings in other psychiatric disorders and suggests that alterations may already occur during early stages of brain development. Our findings support the idea that altered cortical folding might represent a trait characteristic of the disorder although longitudinal studies are needed to clarify the trajectory of this morphological measure in OCD.

Empirical tests of natural selection-based evolutionary accounts of ADHD: a systematic review

OBJECTIVE

ADHD is a prevalent and highly heritable mental disorder associated with significant impairment, morbidity and increased rates of mortality. This combination of high prevalence and high morbidity/mortality seen in ADHD and other mental disorders presents a challenge to natural selection-based models of human evolution. Several hypotheses have been proposed in an attempt to resolve this apparent paradox. The aim of this study was to review the evidence for these hypotheses.

METHODS

We conducted a systematic review of the literature on empirical investigations of natural selection-based evolutionary accounts for ADHD in adherence with the PRISMA guideline. The PubMed, Embase, and PsycINFO databases were screened for relevant publications, by combining search terms covering evolution/selection with search terms covering ADHD.

RESULTS

The search identified 790 records. Of these, 15 full-text articles were assessed for eligibility, and three were included in the review. Two of these reported on the evolution of the seven-repeat allele of the ADHD-associated dopamine receptor D4 gene, and one reported on the results of a simulation study of the effect of suggested ADHD-traits on group survival. The authors of the three studies interpreted their findings as favouring the notion that ADHD-traits may have been associated with increased fitness during human evolution. However, we argue that none of the three studies really tap into the core symptoms of ADHD, and that their conclusions therefore lack validity for the disorder.

CONCLUSIONS

This review indicates that the natural selection-based accounts of ADHD have not been subjected to empirical test and therefore remain hypothetical.

An Allometric Analysis of Sex and Sex Chromosome Dosage Effects on Subcortical Anatomy in Humans

Structural neuroimaging of humans with typical and atypical sex-chromosome complements has established the marked influence of both Yand X-/Y-chromosome dosage on total brain volume (TBV) and identified potential cortical substrates for the psychiatric phenotypes associated with sex-chromosome aneuploidy (SCA). Here, in a cohort of 354 humans with varying karyotypes (XX, XY, XXX, XXY, XYY, XXYY, XXXXY), we investigate sex and SCA effects on subcortical size and shape; focusing on the striatum, pallidum and thalamus. We find large effect-size differences in the volume and shape of all three structures as a function of sex and SCA. We correct for TBV effects with a novel allometric method harnessing normative scaling rules for subcortical size and shape in humans, which we derive here for the first time. We show that all three subcortical volumes scale sublinearly with TBV among healthy humans, mirroring known relationships between subcortical volume and TBV among species. Traditional TBV correction methods assume linear scaling and can therefore invert or exaggerate sex and SCA effects on subcortical anatomy. Allometric analysis restricts sex-differences to: (1) greater pallidal volume (PV) in males, and (2) relative caudate head expansion and ventral striatum contraction in females. Allometric analysis of SCA reveals that supernumerary X- and Y-chromosomes both cause disproportionate reductions in PV, and coordinated deformations of striatopallidal shape. Our study provides a novel understanding of sex and sex-chromosome dosage effects on subcortical organization, using an allometric approach that can be generalized to other basic and clinical structural neuroimaging settings.

Exploring factors related to the anger superiority effect in children with Autism Spectrum Disorder

Despite face and emotion recognition deficits, individuals with Autism Spectrum Disorder (ASD) appear to experience the anger superiority effect, where an angry face in a crowd is detected faster than a neutral face. This study extended past research to examine the impacts of ecologically valid photographic stimuli, gender and anxiety symptoms on the anger superiority effect in children with and without ASD. Participants were 81, 7-12year old children, 42 with ASD matched on age, gender and perceptual IQ to 39 typically developing (TYP) children. The photographic stimuli did not impact on task performance in ASD with both groups exhibiting the anger superiority effect. There were no gender differences and no associations with anxiety. Age was associated with the effect in the TYP but not ASD group. These findings confirm a robust effect of speeded detection of threat in ASD which does not appear to be confounded by gender or anxiety, but may have different underlying age-associated mechanisms.

Distinguishing autism from co-existing conditions: a behavioural profiling investigation

Purpose

– Autism spectrum disorder (ASD) is a lifelong neurodevelopmental condition for which there is no known cure. The rate of psychiatric comorbidity in autism is extremely high, which raises questions about the nature of the co-occurring symptoms. It is unclear whether these additional conditions are true comorbid conditions, or can simply be accounted for through the ASD diagnosis. The paper aims to discuss this issue.

Design/methodology/approach

– A number of questionnaires and a computer-based task were used in the current study. The authors asked the participants about symptoms of ASD, attention deficit hyperactivity disorder (ADHD) and anxiety, as well as overall adaptive functioning.

Findings

– The results demonstrate that each condition, in its pure form, can be clearly differentiated from one another (and from neurotypical controls). Further analyses revealed that when ASD occurs together with anxiety, anxiety appears to be a separate condition. In contrast, there is no clear behavioural profile for when ASD and ADHD co-occur.

Research limitations/implications

– First, due to small sample sizes, some analyses performed were targeted to specific groups (i.e. comparing ADHD, ASD to comorbid ADHD+ASD). Larger sample sizes would have given the statistical power to perform a full scale comparative analysis of all experimental groups when split by their comorbid conditions. Second, males were over-represented in the ASD group and females were over-represented in the anxiety group, due to the uneven gender balance in the prevalence of these conditions. Lastly, the main profiling techniques used were questionnaires. Clinical interviews would have been preferable, as they give a more objective account of behavioural difficulties.

Practical implications

– The rate of psychiatric comorbidity in autism is extremely high, which raises questions about the nature of the co-occurring symptoms. It is unclear whether these additional conditions are true comorbid conditions, or can simply be accounted for through the ASD diagnosis.

Social implications

– This information will be important, not only to healthcare practitioners when administering a diagnosis, but also to therapists who need to apply evidence-based treatment to comorbid and stand-alone conditions.

Originality/value

– This study is the first to investigate the nature of co-existing conditions in ASD in a New Zealand population.

Are ASD and ADHD a Continuum? A Comparison of Pathophysiological Similarities Between the Disorders

OBJECTIVE

The objective of this study was to review and compare the similarities between autism spectrum disorder (ASD) and ADHD with regard to symptomatology, neurological deficits, metabolic and endocrine-related conditions, and brain pathology.

METHOD

A comprehensive review of the relevant research literature was carried out.

RESULTS

A number of important similarities between ASD and ADHD were identified, including recent increases in prevalence, male-biased incidence, shared involvement of sensory processing, motor and impulse control, abnormal patterns of neural connectivity, and sleep disturbances. Studies suggest involvement of androgen metabolism, impaired methylation, and heavy metal toxicity as possible contributing factors for both disorders.

CONCLUSION

ASD and ADHD share a number of features and pathophysiological conditions, which suggests that the two disorders may be a continuum and have a common origin.

Lateralisation abnormalities in obsessive-compulsive disorder: a line bisection study

OBJECTIVE

Asymmetry in brain structure and function is implicated in the pathogenesis of psychiatric disorders. Although right hemisphere abnormality has been documented in obsessive-compulsive disorder (OCD), cerebral asymmetry is rarely examined. Therefore, in this study, we examined anomalous cerebral asymmetry in OCD patients using the line bisection task.

METHODS

A total of 30 patients with OCD and 30 matched healthy controls were examined using a reliable and valid two-hand line bisection (LBS) task. The comparative profiles of LBS scores were analysed using analysis of covariance.

RESULTS

Patients with OCD bisected significantly less number of lines to the left and had significant rightward deviation than controls, indicating right hemisphere dysfunction. The correlations observed in this study suggest that those with impaired laterality had more severe illness at baseline.

CONCLUSIONS

The findings of this study indicate abnormal cerebral lateralisation and right hemisphere dysfunction in OCD patients.

Spontaneous parkinsonisms and striatal impairment in neuroleptic free youth at ultrahigh risk for psychosis

Background:

Spontaneous movement abnormalities, occurring independent of medication status, are thought to reflect basal ganglia pathology in patients at ultrahigh risk (UHR) for psychosis. To date, the research literature has primarily focused on movements associated with elevated striatal dopamine (i.e., hyperkinesia) while little is known about motor symptoms associated with low levels of subcortical dopamine (i.e., spontaneous parkinsonisms; SPs). As SPs (e.g., bradykinesia) may be governed by distinct neural mechanisms, this line of research can provide a clearer picture of the etiological processes in the prodrome.

Aims:

To examine SPs and striatal structural correlates in youth at risk for psychosis.

Methods:

A total of 81 (35 UHR, 46 healthy controls) adolescents were administered a structured clinical interview, structural MRI scan, and handwriting kinematic analysis capable of assessing SPs that are not detectable by traditional observer-based inventories.

Results:

The UHR group exhibited significant decreased velocity scaling (indicative of SPs), t(79)=−2.65, P⩽0.01, as well as decreased ipsilateral t(68)=−3.16, P⩽0.001 and contralateral t(68)=−3.32, P⩽0.001 putamen volume compared with the healthy control group. Further, decreased velocity scaling was significantly associated with smaller ipsilateral putamen r(68)=0.23, P⩽0.05, 95% confidence interval (CI) (−0.005, 0.44), left r(68)=0.23, P⩽0.05, 95% CI (−0.005, 0.44) and right r(68)=0.21, P⩽0.05, 95% CI (−0.03, 0.42) caudate volume, as well as increased positive r(79)=−0.20, P=0.05, 95% CI (−0.40, −0.02) and negative r(79)=−0.27, P⩽0.05, 95% CI (−0.46, −0.06) symptoms across the sample.

Conclusions:

These findings represent the first evidence for hypokinetic movement abnormalities in the UHR period, indicating that pathophysiological processes in UHR patients may also involve hypodopaminergia. The results implicate a dopamine-induced imbalance contributing to frontal–subcortical circuit dysfunction in the psychosis prodrome.

In vivo evidence of neurophysiological maturation of the human adolescent striatum

Maturation of the striatum has been posited to play a primary role in observed increases in adolescent sensation-seeking. However, evidence of neurophysiological maturation in the human adolescent striatum is limited. We applied T2*-weighted imaging, reflecting indices of tissue-iron concentration, to provide direct in vivo evidence of neurophysiological development of the human adolescent striatum. Multivariate pattern analysis (MVPA) of striatal T2*-weighted signal generated age predictions that accounted for over 60% of the sample variance in 10-25 year olds, using both task-related and resting state fMRI. Dorsal and ventral striatum showed age related increases and decreases respectively of striatal neurophysiology suggesting qualitative differences in the maturation of limbic and executive striatal systems. In particular, the ventral striatum was found to show the greatest developmental differences and contribute most heavily to the multivariate age predictor. The relationship of the T2*-weighted signal to the striatal dopamine system is discussed. Together, results provide evidence for protracted maturation of the striatum through adolescence.

Neuropsychological and Clinical Profiles of Children and Adolescents Diagnosed with Childhood Obsessive Compulsive Disorder

INTRODUCTION

The differential features of childhood-onset obsessive compulsive disorder (OCD) compared to adult-onset OCD are being more of a focus of attention in recent years. The aim of this study was to determine the clinical and neuropsychological profiles of children and adolescents diagnosed with childhood-onset OCD and to investigate the association between the duration, severity, comorbidity, and family history of the disorder and clinical and neuropsychological functional impairments.

METHODS

Thirty-five OCD patients (patient group) and 35 healthy control subjects (control group) between 8-15 years of age were included. To investigate the neuropsychological profiles, the Wisconsin Card Sorting Test (WCST), Stroop Test, and Continuous Performance Test (CPT) were applied. To assess the clinical and behavioral profiles, the Children's Depression Inventory (CDI), Conner's Parent Rating Scale (CPRS-48), and the Yale Brown Obsessive Compulsive Scale (YB-OCS) and Yale Global Tic Severity Rating Scale (YGTSRS) were given.

RESULTS

Based on the performance in the WCST, Stroop Test, and SPT, the results of the study reveal that childhood-onset OCD patients have statistically significant worse performance compared to healthy controls in terms of executive functions, sustained attention, and motor inhibition tasks. Excluding the comorbid diagnoses, childhood-onset OCD patients did not show a difference in behavioral problems, but they had higher levels of anxiety compared to healthy controls.

CONCLUSION

The findings of this study reveal that independent of the duration, severity, comorbid problems, and anxiety levels, the disorder itself is associated with worse performance in executive functions, attention, and motor inhibition processes, and a positive family history of OCD is an important risk factor. Long-term follow-up studies with patients diagnosed with childhood-onset OCD would be a logical next step in order to determine the cause-effect relation between the disorder and cognitive impairments.

Nonhuman primate models in the genomic era: a paradigm shift

Because of their strong similarities to humans across physiologic, developmental, behavioral, immunologic, and genetic levels, nonhuman primates are essential models for a wide spectrum of biomedical research. But unlike other animal models, nonhuman primates possess substantial outbred genetic variation, reducing statistical power and potentially confounding interpretation of results in research studies. Although unknown genetic variation is a hindrance in studies that allocate animals randomly, taking genetic variation into account in study design affords an opportunity to transform the way that nonhuman primates are used in biomedical research. New understandings of how the function of individual genes in rhesus macaques mimics that seen in humans are greatly advancing the rhesus macaques utility as research models, but epistatic interaction, epigenetic regulatory mechanisms, and the intricacies of gene networks limit model development. We are now entering a new era of nonhuman primate research, brought on by the proliferation and rapid expansion of genomic data. Already the cost of a rhesus macaque genome is dwarfed by its purchase and husbandry costs, and complete genomic datasets will inevitably encompass each rhesus macaque used in biomedical research. Advancing this outcome is paramount. It represents an opportunity to transform the way animals are assigned and used in biomedical research and to develop new models of human disease. The genetic and genomic revolution brings with it a paradigm shift for nonhuman primates and new mandates on how nonhuman primates are used in biomedical research.

Developmental changes in the organization of functional connections between the basal ganglia and cerebral cortex

The basal ganglia (BG) comprise a set of subcortical nuclei with sensorimotor, cognitive, and limbic subdivisions, indicative of functional organization. BG dysfunction in several developmental disorders suggests the importance of the healthy maturation of these structures. However, few studies have investigated the development of BG functional organization. Using resting-state functional connectivity MRI (rs-fcMRI), we compared human child and adult functional connectivity of the BG with rs-fcMRI-defined cortical systems. Because children move more than adults, customized preprocessing, including volume censoring, was used to minimize motion-induced rs-fcMRI artifact. Our results demonstrated functional organization in the adult BG consistent with subdivisions previously identified in anatomical tracing studies. Group comparisons revealed a developmental shift in bilateral posterior putamen/pallidum clusters from preferential connectivity with the somatomotor "face" system in childhood to preferential connectivity with control/attention systems (frontoparietal, ventral attention) in adulthood. This shift was due to a decline in the functional connectivity of these clusters with the somatomotor face system over development, and no change with control/attention systems. Applying multivariate pattern analysis, we were able to reliably classify individuals as children or adults based on BG-cortical system functional connectivity. Interrogation of the features driving this classification revealed, in addition to the somatomotor face system, contributions by the orbitofrontal, auditory, and somatomotor hand systems. These results demonstrate that BG-cortical functional connectivity evolves over development, and may lend insight into developmental disorders that involve BG dysfunction, particularly those involving motor systems (e.g., Tourette syndrome).

Creative thinking as orchestrated by semantic processing vs. cognitive control brain networks

Creativity is primarily investigated within the neuroscientific perspective as a unitary construct. While such an approach is beneficial when trying to infer the general picture regarding creativity and brain function, it is insufficient if the objective is to uncover the information processing brain mechanisms by which creativity occurs. As creative thinking emerges through the dynamic interplay between several cognitive processes, assessing the neural correlates of these operations would enable the development and characterization of an information processing framework from which to better understand this complex ability. This article focuses on two aspects of creative cognition that are central to generating original ideas. "Conceptual expansion" refers to the ability to widen one's conceptual structures to include unusual or novel associations, while "overcoming knowledge constraints" refers to our ability to override the constraining influence imposed by salient or pertinent knowledge when trying to be creative. Neuroimaging and neuropsychological evidence is presented to illustrate how semantic processing and cognitive control networks in the brain differentially modulate these critical facets of creative cognition.

Focusing on Cause or Cure?: Priorities and Stakeholder Presence in Childhood Psychiatry Research

BACKGROUND

Biomedical research is influenced by many factors, including the involvement of stakeholder groups invested in research outcomes. Stakeholder involvement in research efforts raise questions of justice as their specific interests and motivations play a role in directing research resources that ultimately produce knowledge shaping how different conditions (and affected individuals) are understood and treated by society. This issue is highly relevant to child psychiatry research where diagnostic criteria and treatment strategies are often controversial. Biological similarities and stakeholder differences between attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) provide an opportunity to explore this issue by comparing research foci and stakeholder involvement in these conditions.

METHODS

A subset of ADHD and ASD research articles published between 1970-2010 were randomly selected from the PubMed database and coded for research focus, funding source(s), and author-reported conflicts of interest (COIs). Chi-square analyses were performed to identify differences between and within ADHD and ASD research across time.

RESULTS

The proportion of ADHD research dedicated to basic, description, and treatment research was roughly similar and remained stable over time, while ASD research showed a significant increase in basic research over the past decade. Government was the primary research funder for both conditions, but for-profit funders were a notable presence in ADHD research, while joint-funding efforts between non-profit and government funders were a notable presence in ASD research. Lastly, COIs were noted more frequently in ADHD than in ASD research.

CONCLUSIONS

Our study shows significant differences in research foci and funding sources between the conditions, and identifies the specific involvement of for-profit and non-profit groups in ADHD and ASD, respectively. Our findings highlight the relationship between stakeholders outside the research community and research trajectories and suggest that examinations of these relationships must be included in broader considerations of biomedical research ethics.

Autism spectrum disorder is associated with ventricular enlargement in a low birth weight population

OBJECTIVE

To determine the relation of neonatal cranial ultrasound abnormalities to autism spectrum disorders (ASD) in low birth weight (LBW) adult survivors, a population at increased ASD risk.

STUDY DESIGN

This is a secondary analysis of a prospectively-followed regional birth cohort of 1105 LBW infants systematically screened for perinatal brain injury with cranial ultrasound in the first week of life and later assessed for ASD using a two-stage process [screening at age 16 years (n = 623) followed by diagnostic assessment at age 21 years of a systematically selected subgroup of those screened (n = 189)]; 14 cases of ASD were identified. For this analysis, cranial ultrasound abnormalities were defined as ventricular enlargement (indicative of diffuse white matter injury), parenchymal lesions (indicative of focal white matter injury), and isolated germinal matrix/intraventricular hemorrhage.

RESULTS

Compared with no cranial ultrasound abnormalities, any type of white matter injury (ventricular enlargement and/or parenchymal lesion) tripled the risk for screening positively for ASD [3.0 (2.2, 4.1)]. However, the risk of being diagnosed with ASD depended on type of white matter injury. With ventricular enlargement, the risk of ASD diagnosis was almost seven-fold that of no cranial ultrasound abnormality [6.7 (2.3, 19.7)], and no elevated risk was found for parenchymal lesion without ventricular enlargement [1.8 (0.2, 13.6)]. Isolated germinal matrix/intraventricular hemorrhage did not increase risk for a positive ASD screen or diagnosis.

CONCLUSION

In LBW neonates, cranial ultrasound evidence of ventricular enlargement is a strong and significant risk factor for subsequent development of rigorously-diagnosed ASD.

Differential role of the Mentalizing and the Mirror Neuron system in the imitation of communicative gestures

Successful social interaction requires recognising the intention of another person's communicative gestures. At a neural level, this process may involve neural activity in different systems, such as the mentalizing system (MS) and the mirror neuron system (MNS). The aim of the present study was to explore the neural correlates of communicative gestures during observation and execution of these gestures. Twenty participants watched video clips of an actor executing social gestures (S), non-social gestures (NS) and meaningless gestures (ML). During fMRI data acquisition, participants were asked to observe (O) and subsequently to execute (E) one of two tasks: imitate the gesture presented (IMI) or perform a motor control task (CT). For the contrast IMI>CT we found activations in the core areas of the MNS [inferior parietal lobule (IPL) and inferior frontal cortex, the posterior part of pars opercularis], as well as in areas related to the MS [superior temporal sulcus (STS) and middle cingulate cortex]. For S>NS, we found activations in the left medial orbitofrontal cortex (mOFC), right superior frontal cortex and middle cingulate cortex. The interaction of stimulus condition (S vs NS) and task (IMI vs CT) revealed activation in the right IPL. For the interaction between observation vs execution (O vs E), task (IMI vs CT) and stimulus condition (S vs NS) we found activation in the right mOFC. Our data suggest that imitation is differentially processed in the MNS as well as in the MS. The activation in IPL is enhanced during the processing of social gestures most likely due to their communicative intention. The activation of IPL together with medial frontal areas may contribute to mentalizing processes. The interaction in the mOFC suggests an involvement of self-referential processes in the processing of social gesture.

Creative cognition and the brain: dissociations between frontal, parietal-temporal and basal ganglia groups

The objective of the study was to investigate creativity in relation to brain function by assessing creative thinking in various neurological populations. Several measures were employed to assess different facets of creative thinking in clinical groups with frontal lobe, basal ganglia or parietal-temporal lesions relative to matched healthy control participants. The frontal group was subdivided into frontolateral, frontopolar and frontal-extensive groups. Hierarchical regression analyses were employed to assess the significance levels associated with the effects after accounting for IQ differences between the groups. Findings were only considered noteworthy if they at least suggested the presence of a strong trend and were accompanied by medium to large effect sizes. The parietal-temporal and frontolateral groups revealed poorer overall performance with the former demonstrating problems with fluency related measures, whereas the latter were also less proficient at producing original responses. In contrast, the basal ganglia and frontopolar groups demonstrated superior performance in the ability to overcome the constraints imposed by salient semantic distractors when generating creative responses. In summary, the dissociations in the findings reveal the selective involvement of different brain regions in diverse aspects of creativity. Lesion location posed selective limitations on the ability to generate original responses in different contexts, but not on the ability to generate relevant responses, which was compromised in most patient groups. The noteworthy findings from this exploratory study of enhanced performance in specific aspects of creative cognition following brain damage are discussed with reference to the generic idea that superior creative ability can result from altered brain function.

Neonatal head ultrasound abnormalities in preterm infants and adolescent psychiatric disorders

CONTEXT

Infants born prematurely are at risk for a perinatal encephalopathy characterized by white and gray matter injuries that affect subsequent cortical development and neural connectivity and potentially increase risk for later psychiatric disorder.

OBJECTIVE

To determine the relation of perinatal brain injury, as detected by neonatal head ultrasound, to psychiatric disorders in adolescents who were born prematurely.

DESIGN

Prospective cohort.

SETTING

Community.

PARTICIPANTS

Adolescent survivors of a population-based low-birth-weight (<2000 g; 96% preterm; born 1984-1987) cohort (n = 1105) screened as neonates with serial head ultrasounds. Neonatal head ultrasound abnormalities were categorized as either (1) germinal matrix and/or intraventricular hemorrhage or (2) parenchymal lesions and/or ventricular enlargement. Of 862 eligible survivors, 628 (72.9%) were assessed at age 16 years. The sample consisted of 458 nondisabled survivors assessed in person. Main Outcome Measure  Adolescent current and lifetime psychiatric disorders assessed with parent report on the Diagnostic Interview Schedule for Children-IV.

RESULTS

Compared with no abnormality, germinal matrix/intraventricular hemorrhage increased risk for current major depressive disorder (odds ratio, 2.7; 95% confidence interval, 1.0-6.8) and obsessive-compulsive disorder (9.5; 3.0-30.1). Parenchymal lesions/ventricular enlargement increased risk for current attention-deficit/hyperactivity disorder-inattentive type (odds ratio, 7.6; 95% confidence interval, 2.0-26.5), tic disorders (8.4; 2.4-29.6), and obsessive-compulsive disorder (7.6; 1.39-42.0). Parenchymal lesions/ventricular enlargement were not related to lifetime attention-deficit/hyperactivity disorder-inattentive type, but all other relations were similar for lifetime disorders. Control for other early risk factors did not alter these relations. Most of these relations persisted with control for concurrent cognitive or motor problems.

CONCLUSION

In preterm infants, 2 distinct types of perinatal brain injury detectable with neonatal head ultrasound selectively increase risk in adolescence for psychiatric disorders in which dysfunction of subcortical-cortical circuits has been implicated.

Age-related changes in visual pseudoneglect

Pseudoneglect is a slight but consistent leftward attentional bias commonly observed in healthy young populations, purportedly explained by right hemispheric dominance. It has been suggested that normal aging might be associated with a decline of the right hemisphere. According to this hypothesis, a few studies have shown that elderly tend to exhibit a rightward attentional bias in line bisection. In the present study, we tested this hypothesis in young and older participants using a perceptual landmark task. Results yield evidence for an age-related shift, from a strong attentional leftward bias in young adults toward a suppressed or even a reversed bias in the elderly. Right hemisphere impairment coupled to a left hemispheric compensation might explain the perceptual shift observed in older adults. However, a decline in corpus callosum function cannot be excluded. Alternatively, these results may be in agreement with the hypothesis of an age-related specific inhibition of return dysfunction, an overt attentional orienting mechanism, and/or a decrease of dopamine.

White matter integrity in Asperger syndrome: a preliminary diffusion tensor magnetic resonance imaging study in adults

BACKGROUND

Autistic Spectrum Disorder (ASD), including Asperger syndrome and autism, is a highly genetic neurodevelopmental disorder. There is a consensus that ASD has a biological basis, and it has been proposed that it is a "connectivity" disorder. Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) allows measurement of the microstructural integrity of white matter (a proxy measure of "connectivity"). However, nobody has investigated the microstructural integrity of whole brain white matter in people with Asperger syndrome.

METHODS

We measured the fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD) of white matter, using DT-MRI, in 13 adults with Asperger syndrome and 13 controls. The groups did not differ significantly in overall intelligence and age. FA, MD and RD were assessed using whole brain voxel-based techniques.

RESULTS

Adults with Asperger syndrome had a significantly lower FA than controls in 13 clusters. These were largely bilateral and included white matter in the internal capsule, frontal, temporal, parietal and occipital lobes, cingulum and corpus callosum.

CONCLUSIONS

Adults with Asperger syndrome have widespread significant differences from controls in white matter microstructural integrity.

Neurocognitive performance in children with ADHD and OCD

Attention-deficit/hyperactivity Disorder (ADHD) and obsessive-compulsive disorder (OCD) have both been linked to dysfunction in the cortico-striato-thalamo-cortical circuitry (CSTCC). However, the exact nature of neurocognitive deficits remains to be investigated in both disorders. We applied two neuropsychological tasks that tap into different functions associated with the CSTCC, namely a serial reaction time (SRT) task, developed to assess implicit sequence learning, and a delay aversion (DA) task in order to assess abnormal motivational processes. The performance data of boys with ADHD (n=20), OCD (n=20) and healthy controls (n=25), all aged 10-18 years, were compared. Subjects with ADHD less frequently chose the larger, more delayed reward compared to those with OCD and controls, while subjects with OCD showed impaired implicit learning. In contrast, the ADHD group was unimpaired in their implicit learning behavior and the OCD group was not characterized by a DA style. Within the OCD-group, severity of obsessions was associated with implicit learning deficits and impulsive symptoms with DA in the ADHD-group. This double dissociation highlights the distinct cognitive dysfunctions associated with ADHD and OCD and might possibly point to different neural abnormalities in both disorders.

Threat-detection in child development: an evolutionary perspective

Evidence for developmental aspects of fear-targets and anxiety suggests a complex but stable pattern whereby specific kinds of fears emerge at different periods of development. This developmental schedule seems appropriate to dangers encountered repeatedly during human evolution. Also consistent with evolutionary perspective, the threat-detection systems are domain-specific, comprising different kinds of cues to do with predation, intraspecific violence, contamination-contagion and status loss. Proper evolutionary models may also be relevant to outstanding issues in the domain, notably the connections between typical development and pathology.

MRI study of the cavum septum pellucidum in obsessive-compulsive disorder

The cavum septum pellucidum (CSP), a putative marker of neurodevelopmental anomaly, has been associated with an increased risk of several psychiatric disorders. The purpose of this study was to evaluate the CSP in patients with obsessive-compulsive disorder (OCD) compared with healthy control subjects. Seventy-one patients with OCD and 71 healthy volunteers matched for age and sex were evaluated with magnetic resonance imaging. We evaluated the CSP using criteria employed in previous studies: presence of the CSP, length of the CSP, and overall size of the CSP, measured in five grades, ranging from grades 0 (no CSP) to 4 (severe CSP). We evaluated OCD symptom severity using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The CSP presence was significantly greater in the OCD group (60.6%) than in control subjects (29.6%), and CSP size grade was significantly larger in the OCD group (chi(2) = 15.609, P = 0.004). CSP length showed no significant group difference. Among patients with OCD, those with a CSP had higher scores on the obsession subscale of the Y-BOCS than those without a CSP (Z = -2.358, P = 0.018), while they did not show significant difference from those without a CSP in the compulsion subscale of the Y-BOCS, age, duration of illness, or age at onset. These results indicate that neurodevelopmental alterations in midline structures might contribute to the pathogenesis of OCD.

Antithetical asymmetry in schizophrenia and bipolar affective disorder: a line bisection study

OBJECTIVE

Evolutionary theories link the pathogenesis of psychosis with anomalous brain asymmetry. Research shows that aberrant lateralization is linked to schizophrenia with elevated rates of left-handedness and reversal of normal cerebral asymmetries. However, lateralization is underexamined in bipolar affective disorder (BPAD) and the available literature suggests the possibility of greater lateralization, which is diametrically opposite to what is observed in schizophrenia. For the first time, we report concurrent analyses of asymmetry in BPAD and schizophrenia using a line bisection task.

METHODS

We examined 164 subjects (31 patients with BPAD in remission, 30 patients with schizophrenia, and 103 healthy controls) using a two-hand line bisection task with established methodology. Raters with good inter-rater reliability (intraclass correlation coefficient > 0.8) measured deviation from the center. Task performance was compared using analysis of covariance with age, sex, and education as covariates.

RESULTS

Study groups did not differ significantly on age, sex, and handedness (p > 0.06). Patients (both schizophrenia and BPAD) had significantly more errors in identifying the center than controls (p < 0.001). Patients with schizophrenia bisected fewer lines at center than controls and BPAD subjects (p < 0.001). Using their right hand, schizophrenia patients had significant rightward deviation and BPAD patients had leftward deviation (p = 0.001). A significant interaction between diagnosis and direction of deviation (p = 0.01) was noted, with significant rightward deviation in schizophrenia and a trend toward leftward deviation in BPAD.

CONCLUSIONS

Study findings suggest attenuation of normal pseudoneglect in schizophrenia and accentuation of normal pseudoneglect in BPAD, indicating lesser lateralization in schizophrenia and possibly greater lateralization in BPAD. From an evolutionary perspective, schizophrenia and BPAD might have antithetical origins.