Is Schizophrenia a lateralized brain disorder? Editor's introduction

Global and Specific Cortical Volume Asymmetries in Individuals With Psychosis Risk Syndrome and Schizophrenia: A Mixed Cross-sectional and Longitudinal Perspective

Cortical volumetric asymmetry (CVA) has been widely observed in individuals with psychosis, and is associated with etiological risk factors (e.g., genetics, neuromaturation) and treatment response. However, it is unclear whether CVA abnormalities emerge before psychotic illness onset. Understanding whether CVA manifests in clinical high-risk (CHR)-compared with healthy controls and schizophrenia patients (SCZ)-over time may inform our understanding of pathogenic factors. A total of 233 individuals: 73 CHR, 112 healthy controls, and 48 SCZ underwent an MRI and clinical interviews. Ninety-four individuals including healthy volunteers (HV) (n = 49) and CHR (n = 45), completed another scan at 12-months. CVA was compared by lobe in a repeated-measure design across groups, then nested by time in a longitudinal model. CHR and SCZ groups showed reduced global CVA compared with the healthy control groups but the CHR and SCZ group did not differ from each other. A group by lobe interaction indicated the presence of lobe specific reductions in frontal and cingulate CVA. Cingulate CVA was reduced in CHR and SCZ groups compared to HC groups but did not differ from each other. Frontal CVA was reduced in the older healthy controls compared with younger-HC and CHR, but did not differ from the similarly aged SZ group. CVA is similarly impacted in SCZ and CHR groups, potentially reflecting pathogenic processes. Longitudinal analyses provided further support for the neurodevelopmental hypothesis as CHR exhibited longitudinal changes in opposite directions from normative neuromaturation in HV, which was related to increasing risk for psychosis in the CHR.

Handedness and schizotypy: The potential effect of changing the writing-hand

Mixed-handedness, which has been associated with schizotypy in recent studies, might exist for at least two different reasons: it is innate or it has been forced. We examined whether the association between mixed-handedness and schizotypy differs depending on its source. We enrolled 3485 college students in Taiwan. We used both the Perceptual Aberration Scale and Schizotypal Personality Questionnaire to assess schizotypy, and the Annett Hand Preference Questionnaire to assess handedness. Two ways of classifying handedness were examined: the three-way classification based on Annett's categories and mixed- vs. non-mixed-handedness based on Degree of Handedness. Both mixed-handedness groups showed higher positive schizotypy scores. Among mixed handers, those who had been required to change their writing hand from left to right had higher positive schizotypy scores. Being forced to change writing hand seemed to be related to a higher level of schizotypy. The potential effect of the social pressure against using the left hand for writing is discussed.

Abnormalities in hemispheric specialization of caudate nucleus connectivity in schizophrenia

IMPORTANCE

Hemispheric specialization of the human brain is a marker of successful neurodevelopment. Altered brain asymmetry that has been repeatedly reported in schizophrenia may represent consequences of disrupted neurodevelopment in the disorder. However, a complete picture of functional specialization in the schizophrenic brain and its connectional substrates is yet to be unveiled.

OBJECTIVES

To quantify intrinsic hemispheric specialization at cortical and subcortical levels and to reveal potential disease effects in schizophrenia.

DESIGN, SETTING, AND PARTICIPANTS

Resting-state functional connectivity magnetic resonance imaging has been previously used to quantitatively measure hemispheric specialization in healthy individuals in a reliable manner. We quantified the intrinsic hemispheric specialization at the whole brain level in 31 patients with schizophrenia and 37 demographically matched healthy controls from November 28, 2007, through June 29, 2010, using resting-state functional magnetic resonance imaging.

RESULTS

The caudate nucleus and cortical regions with connections to the caudate nucleus had markedly abnormal hemispheric specialization in schizophrenia. Compared with healthy controls, patients exhibited weaker specialization in the left, but the opposite pattern in the right, caudate nucleus (P < .001). Patients with schizophrenia also had a disruption of the interhemispheric coordination among the cortical regions with connections to the caudate nucleus. A linear classifier based on the specialization of the caudate nucleus distinguished patients from controls with a classification accuracy of 74% (with a sensitivity of 68% and a specificity of 78%).

CONCLUSIONS AND RELEVANCE

These data suggest that hemispheric specialization could serve as a potential imaging biomarker of schizophrenia that, compared with task-based functional magnetic resonance imaging measures, is less prone to the confounding effects of variation in task compliance, cognitive ability, and command of language.

Estimation of heritability for varied indexes of handedness

Inconsistent results of the molecular studies for handedness have been reported. One of the key issues involved could be ways of assessing handedness. The current study aimed to identify the index of handedness better reveal the genetic component, which showed higher heritability. We measured handedness using the Annett's handedness questionnaire. The college students participating in this study filled the questionnaire in the class while their first-degree relatives returned questionnaires one to two weeks later. A total of 1,968 subjects returned their questionnaires, including 640 college students and 1,328 first-degree relatives. Among the 449 college students returning at least one handedness questionnaire for their parents, a total of 449 fathers, 440 mothers, and 425 siblings participated in the study. The index of mixed-handedness (e.g., Degree of Handedness) showed highest heritability (0.67), followed by the Hand Preference Index (0.52), and then the Direction of Handedness (0.39). Using an index of mixed-handedness for future molecular studies was suggested.

The cross-cultural nature of the relationship between schizotypy and mixed-handedness

Positive schizotypy is associated with non-right-handedness, which includes left- and mixed-handedness. However, because the underlying mechanisms might be different, it is important to examine whether both left- and mixed-handedness are associated with a high incidence of schizotypy. During 2009-2010, we used both the Perceptual Aberration Scale and Schizotypal Personality Questionnaire to assess 1315 undergraduate students in Taiwan for schizotypy and the Annett handedness questionnaire to assess handedness. Among the three-way classifications based on Annett's grouping, the fully left-handed group appeared to have the lowest score of positive schizotypy; next was the fully right-handed group and then the mixed-handed. Among the three-way classifications driven from cluster analysis, mixed-handers showed highest score of positive schizotypy. When handedness was treated continuously, both direction (e.g., Hand Preference Index) and consistency (e.g., Either hand use score) indicators were significantly correlated with schizotypy. The results of regression analyses showed that the quadratic handedness measure were negatively associated with schizotypy. The results remained similar after correcting for social pressure on left-handedness. In conclusion, the relationship between schizotypy and mixed-handedness appears to be cross-cultural. The dichotomous classification of handedness, right- vs. non-right-handedness, appears to be insufficient. Additional studies on the distinct mechanisms of mixed- and left-handedness are warranted.

A psychometric approach to the relationship between hand-foot preference and auditory hallucinations in the general population: atypical cerebral lateralization may cause an abnormal sense of agency

The present study examined the relationship between the atypical cerebral lateralization pattern represented in hand and foot preferences and schizotypal personality traits, especially proneness to auditory hallucinations as related to a sense of agency. A sense of agency, measured with questionnaires in the present study, is the sense that "I am the one who causes the actions." Although atypical lateralization and an abnormal sense of agency may be related to schizophrenia or schizotypal personality, the connection between them has remained unclear. The present study used cluster analysis to categorize the handedness-footedness combinations. The results indicated that people with right-handedness and left-footedness may have more schizotypal traits and that their abnormal sense of agency may cause schizotypal personality traits. Although the reasons for crossed lateral preference remain unclear, we discuss this in terms of early switching in handedness, which may underlie atypical lateralization and lead to the experience of auditory hallucinations deriving from an abnormal sense of agency.

Handedness and schizotypy in non-psychotic relatives of patients with schizophrenia

Existing studies have found the relationship between handedness and schizotypy to be inconsistent, and had limited generalisability since only highly homogeneous groups have been investigated. This study aimed to examine the relation between handedness and the four schizotypal factors identified from a previous confirmatory factor analysis in a population of high familial loading for schizophrenia. Study participants consisted of non-psychotic first-degree relatives (850 parents and 334 siblings) of sib-pairs who were co-affected with schizophrenia. All participants were interviewed with the Diagnostic Interview for Genetic Studies, which contains a section of the modified Structured Interview for Schizotypy, and the Annett handedness questionnaire. Both categorical and continuous indicators for handedness were examined. Non-right-handed siblings of schizophrenia patients displayed more positive schizotypal features than their right-handed counterparts when the two-way Annett's handedness classification was adopted. No association was found when handedness was treated as continuous. The relationship between handedness and schizotypy was insignificant for parents probably due to the strong social pressure against left-handedness. We concluded that categorical non-right-handedness was associated with positive schizotypy in non-psychotic siblings of schizophrenia patients. The results indicate that an atypical cerebral lateralisation underlying non-right-handedness may be also a contributing factor to positive schizotypy.

Handedness and schizotypy in non-clinical populations: Influence of handedness measures and age on the relationship

This study aimed to evaluate the relation of handedness to schizotypal personality, with the influence of different handedness measures and age on the relationship investigated as well among representative samples of school students and community adults in Taiwan, where social pressure against certain left-handed actions was strong. In a total of 175 primary school students, 1020 junior high-school students, and 342 adult participants aged 20 to 65 years, all the participants completed the 12-item Annett handedness questionnaire, and the latter two groups further completed the Schizotypal Personality Questionnaire (SPQ) and the Perceptual Aberration Scale (PAS). There was a trend of increasing non-right handedness with younger age groups. Two classification methods in handedness, Annett's or Briggs-Nebes' three-category classification, led to very different frequency distribution and relation to schizotypy. For the adolescents, either Annett's classification or quantitative measures (Hand Preference Index and either-hand use scores) in handedness exhibited an association with schizotypy, whereas for the adults the either-hand use score was the only measure that did so. In contrast, no such difference was found using the Briggs-Nebes' classification method. The association of the non-right or mixed handedness was more consistent and of greater magnitude with the positive aspect of schizotypy, especially the PAS and the Cognitive-perceptual Dysfunction of the SPQ. The results highlight the potential of adolescents for future investigation on certain common causes underlying atypical cerebral lateralisation and positive schizotypy.

Asymmetries of cortical shape: Effects of handedness, sex and schizophrenia

Some evidence suggests that sex, handedness and disease processes associated with schizophrenia affect the magnitude and/or direction of structural brain asymmetries. There are mixed findings, however, on how these factors influence cerebral torque, when torque is assessed with linear or volumetric measurements. We obtained MRI data from 67 healthy (30 males, 10 non-dextrals) and 84 schizophrenia subjects (60 males; 16 non-dextrals) and applied cortical pattern matching to spatially relate and compare differences in the surface morphology of the two cerebral hemispheres at high spatial resolution. Asymmetry indices, computed at thousands of matched hemispheric locations, were used to examine effects of sex, handedness and schizophrenia on hemispheric shape asymmetries while controlling for age and the other factors. Highly significant and discriminative right-frontal and left parietal-occipital surface expansions and protrusions (petalias) were mapped within groups. Although hemispheric shape asymmetries appeared less pronounced within female non-dextrals, asymmetry indices were not shown to differ significantly across sex, hand preference or diagnosis, or to reveal interactions of handedness with sex or diagnosis. Our 3D maps of spatially detailed anterior and posterior hemispheric shape asymmetries reflect subtle geometric distortions in hemispheric surface morphology that cannot be characterized with 2D or volumetric methods. Inter-individual variations in hemispheric torque appear minimally influenced by sex, dextrality or disease status. Biological factors driving language dominance or other lateralized brain functions dissociable from handedness, may more closely relate to hemispheric shape asymmetries, while the lateralization of other discrete brain regions may be more influenced by sexually dimorphic factors or by schizophrenia pathophysiology.

Regional brain metabolism in schizophrenia: An FDG-PET study

BACKGROUND

Recent technological advances have established beyond any doubt the biological nature of schizophrenia. Functional neuroimaging using FDG-PET forms an important technique in understanding the biological underpinnings of psychopathology of schizophrenia.

METHODS

Eighteen male patients diagnosed as having schizophrenia and having active psychosis as determined by PANSS were subjected to FDG-PET scanning under resting conditions. The glucose uptake in selected regions of interest was studied across the spectrum of schizophrenia.

RESULTS

Chronicity and severity of illness did not influence cerebral glucose metabolism. Participants with negative schizophrenia had significantly decreased metabolism in all regions of the brain as compared to the positive type. The positive syndrome of schizophrenia was associated with significantly increased glucose metabolism in the medial temporal regions, basal ganglia and left thalamic regions. Hypometabolism was also noted in the cerebellum.

CONCLUSION

While a number of brain areas can be identified as potential causative regions and hypotheses regarding putative mechanisms can be formed, the considerable heterogeneity of schizophrenia poses a great challenge in the precise delineation of the disease process.

Magical ideation and its relation to lateral preference

Schizophrenia and schizotypal personality have been linked to sinistrality as well as ambidextrality. The current study clarifies the relation between laterality and schizotypal personality by administering a battery of laterality questionnaires to measure hand, eye, ear, and foot preference in a group of 933 university students. To determine whether the relationship between schizotypy and laterality is limited to self-report measures, performance asymmetries between the hands were measured with tapping rate. There was no difference between dextrals and sinistrals in schizotypal personality, as indexed by the Magical Ideation (MI) scale. MI was higher, however, for individuals with a weak preference for either hand or eye compared to those with a strong dominance. In addition, individuals inconsistent in their lateral preference across modalities showed higher MI scores. Performance asymmetries had no effect on MI scores. This lack of effect was attributed to the inability of performance measures, such as tapping rate, to identify ambidextrals. The results support research linking schizotypal personality to ambidextrality and weak cerebral dominance and demonstrate that the association extends to modalities other than hand preference.

Hemispheric lateralization patterns and psychotic experiences in healthy subjects

The hypothesis that psychotic experiences in healthy subjects are associated with a dysfunction of the right hemisphere is supported by some, but not all, available studies. Differences in gender composition of study samples may explain in part the divergent findings. The present study was carried out in 42 healthy, right-handed university students. Scores on the Schizophrenia and Paranoia scales of the Minnesota Multidimensional Personality Inventory-2 were used in correlation analyses and to define a High- and a Low-Psychotic group. Brain Electrical Microstates and Low Resolution Electromagnetic Tomography (LORETA) source analyses of the auditory P300 (P3a and P3b) components of the event-related potential, as well as a battery of neuropsychological tests, were used to assess hemispheric functioning. Scores on the Paranoia scale were positively associated with a leftward shift of the P3a topographic descriptors in females but not in males. When comparing High-Psychotic and Low-Psychotic females, a leftward shift of P3a descriptors and an increased cortical activation in left fronto-temporal areas were observed in the High-Psychotic group. Our results demonstrated gender-related differences in the pattern of hemispheric imbalance associated with psychotic experiences in healthy subjects.

Strong mixed-handedness in schizophrenia

There is still considerable discussion of whether schizophrenia is a lateralized brain disorder. In fact, schizophrenic patients appear to exhibit a shift away from dexterity, as confirmed by the majority of the 23 publications dealing with this question (14 positive, seven null, two paradoxical). However, quite a few of these positive studies have distinguished between left-handedness and mixed-handedness (MH), thus lacking specificity. Whereas prior studies failed to specify schizophrenic MH, we could observe a significant relationship between strong MH and schizophrenia in male patients in a relatively small group due to sex differentiation and accurate application of Annett's hand preference questionnaire.

The dynamic approach to neurodevelopmental psychiatric disorders: use of fMRI combined with neuropsychology to elucidate the dynamics of psychiatric disorders, exemplified in ADHD and schizophrenia

The paper discusses the application of fMRI in combination with neuropsychology to neurodevelopmental psychiatric disorders, exemplified on the case of attention deficit hyperactivity disorder (ADHD) in comparison with schizophrenia. The view is presented that ADHD, rather than being a compound of unrelated co-existing deficits, is a pervasive disorder of impulsiveness, which manifests at the motor, emotional, social and cognitive domain. Neuropsychology needs to refine the psychological measurements of these impulsivity symptoms and, in combination with fMRI, provide new insights into the interrelationship between brain and dysfunction and its bi-directional causalities. The suitability of the dynamic technique of functional MRI to assess the dynamic nature of developmental neuropsychiatric disorders is discussed. Brain activation can inform about strategy and compensatory mechanisms at a neuroanatomical level, which are not observable at a psychological level, providing insight into the underlying neurocognitive mechanisms of psychiatric disorders. Data are presented and discussed on opposing neurocognitive activation patterns for patients with ADHD and those with schizophrenia while performing a stop task. Comparisons between patient groups will be essential to address the specificity of neurocognitive mechanisms corresponding to specific neurodevelopmental psychiatric disorders.

Ambidexterity and magical ideation

In a sample of 250 healthy undergraduate students, scores on a scale of magical ideation rose to a peak at the point of ambilaterality on a scale of hand preference, and fell away with increasing right- or left-handedness. This effect mirrors that reported by Crow, Crow, Done, and Leask (1998) who found a dip in academic abilities at the point of ambilaterality, or what they call ''the point of hemispheric indecision''. We relate these findings to genetic theories of laterality in which one allele (RS+) codes for left-cerebral dominance while the other (RS-) leaves laterality to chance. RS-- homozygotes may be susceptible to a lack of dominance, resulting in a disposition to magical ideation and an increased risk of schizophrenia, but also enhanced creativity and lateral thinking.

Schizotypy and the shift from dextrality: a study of handedness in a large non-clinical sample

Numerous previous studies have reported associations between schizophrenia/schizotypy and atypical handedness. While there is broad agreement that schizophrenia/schizotypy is associated with a shift away from typical (strong right) handedness, it is not entirely clear what aspect of atypical handedness is implicated: 'ambiguous' handedness (the absence of hand preference for given actions) or 'mixed handedness' (different hand preferences for different actions). The present study used several indices of handedness (derived from the Annett scale) to address these questions in 3000 + (mostly) University student subjects recruited by electronic mail. It was found that positive schizotypy (indexed by a scale of 'unusual experiences') was associated with both aspects of atypical handedness. These findings are discussed in the light of various possible explanations of the association between handedness and schizophrenia/schizotypy.

Three-dimensional mapping of gyral shape and cortical surface asymmetries in schizophrenia: gender effects

OBJECTIVE

People with schizophrenia exhibit abnormalities in brain structure, often in the left hemisphere. Disturbed structural lateralization is controversial, however, and effects appear mediated by gender. The authors mapped differences between schizophrenic and normal subjects in gyral asymmetries, complexity, and variability across the entire cortex.

METHOD

Asymmetry and shape profiles for 25 schizophrenic patients (15 men) and 28 demographically similar normal subjects (15 men) were obtained for 38 gyral regions, including the sylvian fissure and temporal and postcentral gyri, by using magnetic resonance data and a novel surface-based mesh-modeling approach. Cortical complexity was examined for sex and diagnosis effects in lobar regions. Intragroup variability was quantified and visualized to assess regional group abnormalities at the cortical surface.

RESULTS

The patients showed greater variability in frontal areas than the comparison subjects. They also had significant deviations in gyral complexity asymmetry in the superior frontal cortex. In temporoparietal regions, significant gyral asymmetries were present in both groups. Sex differences were apparent in superior temporal gyral measures, and cortical complexity in inferior frontal regions was significantly greater in men.

CONCLUSIONS

Cortical variability and complexity show regional abnormalities in the frontal cortex potentially specific to schizophrenia. The results indicate highly significant temporoparietal gyral asymmetries in both diagnostic groups, contrary to reports of less lateralization in schizophrenia. Substantially larger study groups are necessary to isolate smaller deviations in surface asymmetries, if present in schizophrenia, suggesting their diagnostic value is minimal.

The contribution of early traumatic events to schizophrenia in some patients: a traumagenic neurodevelopmental model

The current diathesis-stress model of schizophrenia proposes that a genetic deficit creates a predisposing vulnerability in the form of oversenstivity to stress. This model positions all psychosocial events on the stress side of the diathesis-stress equation. As an example of hypotheses that emerge when consideration is given to repositioning adverse life events as potential contributors to the diathesis, this article examines one possible explanation for the high prevalence of child abuse found in adults diagnosed schizophrenic. A traumagenic neurodevelopmental (TN) model of schizophrenia is presented, documenting the similarities between the effects of traumatic events on the developing brain and the biological abnormalities found in persons diagnosed with schizophrenia, including overreactivity of the hypothalamic-pituitary-adrenal (HPA) axis; dopamine, norepinephrine, and serotonin abnormalities; and structural changes to the brain such as hippocampal damage, cerebral atrophy, ventricular enlargement, and reversed cerebral asymmetry. The TN model offers potential explanations for other findings in schizophrenia research beyond oversensitivity to stress, including cognitive impairment, pathways to positive and negative symptoms, and the relationship between psychotic and dissociative symptomatology. It is recommended that clinicians and researchers explore the presence of early adverse life events in adults with psychotic symptoms in order to ensure comprehensive formulations and appropriate treatment plans, and to further investigate the hypotheses generated by the TN model.

Lateralization of cognitive processes in the brain

The lateralization of cognitive processes in the brain is discussed. The traditional view of a language-visuo/spatial dichotomy of function between the hemispheres has been replaced by more subtle distinctions. The use of magnetic resonance imaging (MRI) to study brain morphology has resulted in a renewed focus on the relationship between structural and functional asymmetry. Focus has been on the role played by the planum temporale area in the posterior part of the superior temporal gyrus for language asymmetry, and the possible significance of the larger left planum. The dichotic listening technique is used to illustrate the difference between bottom-up, or stimulus-driven laterality versus top-down, or instruction-driven laterality. It is suggested that the hemispheric dominance observed at any time is the sum result of the dynamic interaction between bottom-up and top-down processing tendencies. Stimulus-driven laterality dominance is always monitored and modulated through top-down cognitive processes, like shifting of attention and changes in arousal. A model of top-down modulation of bottom-up laterality is presented with special reference to the understanding of psychiatric disorders.

Brain hemispheric organization, anxiety, and psychoses

Abnormalities of brain hemispheric organization have been found in a variety of psychiatric disorders. Despite the great amount of data collected and the number of theoretical models elaborated, the role of these abnormalities in the pathogenesis of these disorders remains controversial. This article briefly reviews current concepts of hemispheric functioning, discusses the role of abnormalities of brain hemispheric organization in schizophrenia and in two anxiety disorders (panic disorder and obsessive-compulsive disorder), and outlines a developmental perspective that accounts for the observed abnormalities.

Developmental instability and schizotypy

INTRODUCTION

It has been suggested that evidence of developmental disturbance of cognition and lateralisation in schizophrenia can be best understood from the perspective of developmental stability (DS), an indicator of the extent to which an individual develops according to a specified ontogenic programme in the presence of environmental noise. Higher levels of fluctuating asymmetry (FA; the difference between right and left side of a quantitative morphological trait such as dermatoglyphics) are thought to reflect less DS. We examined this issue for dimensions of schizotypy.

METHODS

Associations between FA, measures of laterality and cognitive function on the one hand, and negative and positive dimensions of schizotypy on the other, were examined in a sample of 260 healthy adolescents aged 11.9-15.6years. FA was measured as a-b ridge count right-left differences. Neuropsychological measures yielded a general cognitive ability score and a frontal function score. Laterality was assessed with the Annett scale.

RESULTS

Measures of psychosis proneness were normally distributed. Negative schizotypy was associated with more FA and lower general cognitive ability in a dose-response fashion. The association with FA was more apparent in boys. No associations existed with laterality or frontal function.

CONCLUSION

The negative dimension of schizotypy may be associated with early developmental instability, resembling the pattern seen in the negative symptom dimension of schizophrenia. Measures of fluctuating asymmetry may be more sensitive with regard to the schizotypy phenotype than measures of laterality.

Schizotypy and leadership: a contrasting model for deficit symptoms, and a possible therapeutic role for sex hormones

Associational loosening, slow and faulty information processing, poor gating of irrelevant stimuli, poor ability to shift attention, poor working memory, passivity, ambivalence, anhedonia, and impaired motor coordination are cardinal features of schizophrenia but, unlike delusions and hallucinations, they are related more to negative/deficit symptoms. As summarized by Bass, numerous studies have correlated leadership with 'ambition, initiative and persistence' (opposite of passivity), 'speed and accuracy of thought', 'finality of decision,' or decisiveness (the opposite of ambivalence), 'mood control, optimism and sense of humor' (opposite of anhedonia), etc. Andreasen et al postulate that a disruption in the circuitry among nodes located in the prefrontal regions, the thalamic nuclei, and the cerebellum produces 'cognitive dysmetria', meaning difficulty in prioritizing, coordinating, and responding to information, and that it can account for the broad diversity of symptoms of schizophrenia. A relationship between cognitive processes and cerebellar and basal ganglia functions, and a role of neocerebellum in rapidly shifting attention, have been demonstrated. The cognitive styles, including a proficiency to quickly shift attention, of several famous leaders are used as examples of this contrasting model. Julius Caesar and Napoleon, for instance, could dictate to up to six secretaries simultaneously, using their exceptional working memories, and proficiency in quickly and effortlessly shifting attention while flawlessly gating irrelevant external and internal stimuli. It is suggested that specific brain imaging studies could illustrate this contrast. Gray et al noted positive correlations between 'dominance', an important leadership trait, and serum levels of dehydroepiandrosterone (DHEA) and testosterone (T), but not of more potent dihydrotestosterone (DHT), in over 1700 older men. Though not scientifically rigorous, the author noted positive correlations (P = 0.0162) between the self-rated ratings of voice depth (promoted by T) and of leadership, but none between those of body hair (DHT dependent) and of leadership in 47 male US National Academy of Sciences members. And 43 male US Senators had deeper voices than 36 male House members (P<0.01) who, in turn, had deeper voices than either of two groups (numbers 102 and 72) of male scientists (P<0.01). Therapeutically, before chlorpromazine, DHEA had been used in young schizophrenics with modest success in improving deficit symptoms. DHEA, or other sex hormones, or some of their natural and synthetic derivatives may prove to be valuable to treat deficit symptoms of schizophrenia in both sexes.