Schizophrenia as an anomaly of development of cerebral asymmetry. A postmortem study and a proposal concerning the genetic basis of the disease

The neuropsychology of schizophrenia

A model is proposed for integrating the neural and cognitive aspects of the positive symptoms of acute schizophrenia, using evidence from postmortem neuropathology and neurochemistry, clinical and preclinical studies of dopaminergic neurotransmission, anatomical connections between the limbic system and basal ganglia, attentional and other cognitive abnormalities underlying the positive symptoms of schizophrenia, specific animal models of some of these abnormalities, and previous attempts to model the cognitive functions of the septohippocampal system and the motor functions of the basal ganglia. Anatomically, the model emphasises the projections from the septohippocampal system, via the subiculum, and the amygdala to nucleus accumbens, and their interaction with the ascending dopaminergic projection to the accumbens. Psychologically, the model emphasises a failure in acute schizophrenia to integrate stored memories of past regularities of perceptual input with ongoing motor programs in the control of current perception. A number of recent experiments that offer support for the model are briefly described, including anatomical studies of limbic-striatal connections, studies in the rat of the effects of damage to these connections, and of the effects of amphetamine and neuroleptics, on the partial reinforcement extinction effect, latent inhibition and the Kamin blocking effect; and studies of the latter two phenomena in acute and chronic schizophrenics.

Effect of chronic antipsychotic treatment on brain structure: a serial magnetic resonance imaging study with ex vivo and postmortem confirmation

BACKGROUND

There is increasing evidence that antipsychotic (APD) may affect brain structure directly. To examine this, we developed a rodent model that uses clinically relevant doses and serial magnetic resonance imaging (MRI), followed by postmortem histopathological analysis to study the effects of APD on brain structures.

METHODS

Antipsychotic , haloperidol, and olanzapine were continuously administered to rats via osmotic minipumps to maintain clinic-like steady state levels for 8 weeks. Longitudinal in vivo MRI scanning (T₂-weighted) was carried out at baseline, 4 weeks, and 8 weeks, after which animals were perfused and their brains preserved for ex vivo MRI scanning. Region of interest analyses were performed on magnetic resonance images (both in vivo as well as ex vivo) along with postmortem stereology using the Cavalieri estimator probe.

RESULTS

Chronic (8 weeks) exposure to both haloperidol and olanzapine resulted in significant decreases in whole-brain volume (6% to 8%) compared with vehicle-treated control subjects, driven mainly by a decrease in frontal cerebral cortex volume (8% to 12%). Hippocampal, corpus striatum, lateral ventricles, and corpus callosum volumes were not significantly different from control subjects, suggesting a differential effect of APD on the cortex. These results were corroborated by ex vivo MRI scans and decreased cortical volume was confirmed postmortem by stereology.

CONCLUSIONS

This is the first systematic whole-brain MRI study of the effects of APD, which highlights significant effects on the cortex. Although caution needs to be exerted when extrapolating results from animals to patients, the approach provides a tractable method for linking in vivo MRI findings to their histopathological origins.

Cerebral asymmetry in schizophrenia

The hemispheres of the human brain are anatomically and functionally asymmetric, and many cognitive and motor functions such as language and handedness are lateralized. This review examines anatomical, psychological, and physiological approaches to the understanding of separate hemispheric functions and their integration. The concept of hemispheric laterality plays a central role in current neuropsychological and pathophysiological models of schizophrenia. Reduced hemispheric asymmetry has also been reported for other mental disorders, for example, bipolar disorder. Recent research reflects an increasing interest in the molecular and population genetics of laterality and its potential link with animal models of schizophrenia. The authors review the principles of laterality and brain asymmetry and discuss the evidence for changes in asymmetry in schizophrenia and other mental disorders.

Folic Acid: Beyond Metabolism

Mandatory and discretionary fortification with folic acid is eliminating deficiency of this vitamin. Blood levels of the vitamin have never been higher, with hematologic folate values commonly exceeding the upper range of calibration. The synthetic analog (pteroylmonoglutamic acid) prevents neural tube defects and lowers homocysteine, both positive attributes, yet negative correlates of pteroylmonoglutamic acid are increasingly reported. These involve increased risk for common cancers (ie, colon, breast, prostate) and antimetabolite effects on natural killer cells and at dihydrofolate reductase, a critical gatekeeper enzyme. This review, however, takes a different, human ecological perspective, examining novel folate-related phenomena distinct from the classic metabolic role of the vitamin in maintaining health and well-being. An argument is developed that at molecular, cellular, and organism levels, folate is crucial to some important events that link light to life.

When cortical development goes wrong: schizophrenia as a neurodevelopmental disease of microcircuits

Schizophrenia probably has a developmental origin. This review refers to three of our published series of studies related to this hypothesis: loss of dendritic spines on cerebral neocortical pyramidal neurons, decreased numerical density of glutamatergic neurons, and microgliosis. First, brains of schizophrenic patients and non-schizophrenic controls were obtained post mortem and blocks of multiple cortical areas impregnated with a Rapid Golgi method. Spines were counted on the dendrites of pyramidal neurons of which the soma was in layer III (which takes part in corticocortical connectivity) and which met strict criteria for impregnation quality. Data were obtained blind: diagnoses were only revealed by a third party after measurements were completed. The mean spine count in all cortical areas studied in the control series was 243 mm(-1) of dendrite and in the schizophrenics 108. Measurements in frontal and temporal association cortex showed the greatest reduction in spine number in schizophrenia (299 in control frontal cortex and 101 in schizophrenics, and 276 mm(-1) in control temporal cortex and 125 in schizophrenics). There was no correlation of spine loss with age at death. Our results support the concept of a neurodevelopmental defect in the neuropil affecting glutamatergic neurons in schizophrenia and may help to explain loss of cortical volume without loss of neurons. In a second part of our study we used an antibody to the kainate receptor subunit GluR 5/6/7 and showed a decrease in numerical density of presumed glutamatergic neurons in schizophrenic orbitofrontal cortex. Finally, as glia play a major role in the developing nervous system, we investigated whether schizophrenia was associated with glial changes in frontal and temporal cortex. Astroglia and microglia were identified in schizophrenic and control brains, using antibodies to glial fibrillary acidic protein (GFAP) and class II human leucocyte antigen (HLA-DR), respectively. Significant increases were found in microglial numerical density in schizophrenics compared with controls: 28% in frontal area 9 (115 cells mm(-2) compared with 89), and a 57% increase in temporal area 22 (139 cells mm(-2) compared with 88). For both areas, astroglia showed no significant differences between schizophrenics and controls. No significant differences were found in cortical thickness or total neuronal numerical density between the two groups. This specific increase in numerical density of microglia in temporal and frontal cortex of chronic schizophrenics, not related to aging, could be related to possible changes in cortical neuropil architecture as revealed by loss of dendritic spines.

Searching for neuropathology: gliosis in schizophrenia

The neuropathology of schizophrenia remains elusive. One indication of this elusiveness is that the literature, in contrast to that on the neuropathology of almost any other disease, deals predominantly with measures of normal structures rather than with the demonstration and characterization of pathological structures. An important exception to this trend has been the continued search, over four decades, for reactive glia. In this article, we review histological and radiological evidence for and against astrocytosis and microgliosis specifically associated with schizophrenia. The studies are generally limited by small samples, flawed designs, and potentially biased methods of counting cells. Interpretation of these studies is further complicated by the frequent presence of glial reactions in older individuals without psychiatric disease. Nonetheless, some of the positive findings in the literature cannot easily be dismissed. A sufficiently large autopsy study, weighted toward younger subjects, could provide a definitive answer, which if positive could be a major step toward finding an underlying pathological process.

Hippocampi, thalami, and accumbens microstructural damage in schizophrenia: a volumetry, diffusivity, and neuropsychological study

Volumetric abnormalities in the subcortical structures have been described in schizophrenia. However, it still has to be clarified if subtle microstructural damage is also present. Thus, we aimed to detect subcortical volume and mean diffusivity (MD) alterations in 45 patients with diagnosis of schizophrenia compared with 45 age-, gender-, and educational attainment-matched healthy comparison (HC) participants, by using a combined volumetry and diffusion tensor imaging (DTI) method. A secondary aim was to identify the neuropsychological correlates of subcortical abnormalities in the schizophrenic group. We found thalami and hippocampi bilaterally and left accumbens to show MD increase in the schizophrenic group. No volumetric decrease was found. Moreover, significant correlations between the MD values in subcortical structures (right thalamus and hippocampus and left accumbens) and working memory performance were found. Thus, subcortical microstructural alterations are present in schizophrenia even in absence of volumetric abnormalities. Furthermore, microstructural damage in subcortical areas is linked to working memory, suggesting the presence of a subtle microstructural subcortical dysfunction in the pathoetiological mechanism underlying high cognitive load performances in schizophrenia. Finally, our findings indicate that MD is a more sensitive marker of brain tissue deficits than signal intensity variations measured in T1-weighted imaging data, consistently with previous reports. Thus, DTI appears to be an invaluable tool to investigate subcortical pathology in schizophrenia, greatly enhancing the ability to detect subtle brain changes in this complex disorder.

Hand preference and hand skill in families with schizophrenia

Direction and degree of handedness in humans are variable between individuals and thought to be in part inherited. Several studies have shown an increase in non-right handedness among patients with schizophrenia, and some have included unaffected relatives. The present study was designed to determine whether reduced right handedness is more frequent among individuals with schizophrenia as compared with their well relatives and whether it clusters within families having multiple ill members. A total of 259 families comprising 418 individuals diagnosed with schizophrenia or schizoaffective disorder, 54 individuals with other psychoses, 145 family members with depression and other minor diagnoses, and 288 unaffected individuals were included. Hand preference was assessed by the Annett Scale and right relative to left hand skill measured using the Tapley-Bryden test. For all assessments of hand preference and hand skill, females were significantly more lateralised towards the right than males. Those individuals with schizophrenia or schizoaffective disorder had significantly less right hand preference than their unaffected relatives when measured as a quantitative index of items from the Annett Scale (p = .019), but not categorically (right, left or mixed). In contrast, there was no difference in hand skill between diagnostic groups. Hand preference was significantly correlated among male-male affected sibling pairs (p = .01) and similar results were found for hand skill among the total group of affected pairs (p = .001). Although these results only partially support a relationship between handedness and schizophrenia, they nevertheless draw attention to sex differences in hand preference and the familial aspects of hand preference in this disorder. More direct approaches to the genetics of cerebral dominance and psychosis are required.

Neuropathology of epilepsy and psychosis: the contributions of J.A.N. Corsellis

Professor J.A.N. Corsellis, whose life and work is recalled here, gained great insight into the meaning of morphological cerebral aberrations found in neuropsychiatric disease through exact neuropathological investigations of tissue specimens obtained from patients with distinct syndromes. He was a leading authority in the field. We have searched and compiled resources relating to J.A.N. Corsellis' life and work, including personal memories from colleagues and data from scientific publications. J.A.N. Corsellis made seminal contributions to the understanding of neuropsychiatric disease; his works substantially added to the understanding of the dementias, schizophrenia and the psychoses, and morphological sequelae of boxing. In seizure disorders, his name is linked to the first description of focal cortical dysplasia and limbic encephalitis, the pathology of status epilepticus and Ammon's horn sclerosis, and the systematic investigation of epilepsy surgery specimens in general. Both his life and work are closely linked to Runwell Hospital, Wickford, Essex and the Maudsley Hospital. During his professional life he established a large brain bank, now known as the Corsellis Collection. J.A.N. Corsellis had significant impact on neuroscience; many of his observations were groundbreaking and are still valid.

Anterior thalamic radiation integrity in schizophrenia: a diffusion-tensor imaging study

The anterior limb of the internal capsule (ALIC) is a white matter structure, the medial portion of which includes the anterior thalamic radiation (ATR) carrying nerve fibers between thalamus and prefrontal cortex. ATR abnormalities have a possible link with cognitive abnormalities and negative symptoms in schizophrenia. We aimed to study the fiber integrity of the ATR more selectively by isolating the medial portion of the ALIC using region-of-interest based methodology. Diffusion-tensor imaging was used to measure the anisotropy of total ALIC (tALIC) and medial ALIC (mALIC) in 39 schizophrenia and 33 control participants, matched for age/gender/handedness. Relationships between anisotropy, psychopathology, and cognitive performance were analyzed. Compared with controls, schizophrenia participants had 4.55% lower anisotropy in right tALIC, and 5.38% lower anisotropy in right mALIC. There were no significant group anisotropy differences on the left. Significant correlations were observed between right ALIC integrity and relevant domains of cognitive function (e.g., executive function, working memory). Our study suggests an asymmetric microstructural change in ALIC in schizophrenia involving the right side, which is only minimally stronger in mALIC, and which correlates with cognitive impairment. Microstructural changes in the ALIC may be linked to cognitive dysfunction in schizophrenia.

Anterior cingulate and paracingulate sulci morphology in patients with schizophrenia

The anterior cingulate cortex is a cerebral region engaged in several emotional and cognitive functions. The aim of this study was to investigate possible anterior cingulate and paracingulate sulcal abnormalities in schizophrenia. Twenty-three patients with DSM-IV diagnoses of schizophrenia were compared with 23 healthy subjects matched for age, gender, and parental socioeconomic status. Magnetic resonance images were used to explore the morphology of these regions, with volume and maximum depth being measured by an automated method of sulcal recognition. Additionally, voxel-based morphometry (VBM) was performed to analyze possible reduction in gray and white matter of the anterior cingulate region. A smaller volume of the left anterior cingulate sulcus (ACS) was observed in patients with schizophrenia when compared with healthy controls. Furthermore, female patients showed a reduction in volume of the left ACS and an increase of the right paracingulate sulcus (PCS) compared to female controls. There was also a significant relationship between the depth of right PCS and neuroleptic exposure. VBM analysis showed a reduction in left anterior cingulate gray matter. These findings provide further evidence of left anterior middle frontal cortex abnormalities in schizophrenia. In addition, the results suggest gender differences in the structural abnormalities of the illness.

Prenatal exposure to phencyclidine produces abnormal behaviour and NMDA receptor expression in postpubertal mice

Several studies have shown the disruptive effects of non-competitive N-methyl-d-aspartate (NMDA) receptor antagonists on neurobehavioural development. Based on the neurodevelopment hypothesis of schizophrenia, there is growing interest in animal models treated with NMDA antagonists at developing stages to investigate the pathogenesis of psychological disturbances in humans. Previous studies have reported that perinatal treatment with phencyclidine (PCP) impairs the development of neuronal systems and induces schizophrenia-like behaviour. However, the adverse effects of prenatal exposure to PCP on behaviour and the function of NMDA receptors are not well understood. This study investigated the long-term effects of prenatal exposure to PCP in mice. The prenatal PCP-treated mice showed hypersensitivity to a low dose of PCP in locomotor activity and impairment of recognition memory in the novel object recognition test at age 7 wk. Meanwhile, the prenatal exposure reduced the phosphorylation of NR1, although it increased the expression of NR1 itself. Furthermore, these behavioural changes were attenuated by atypical antipsychotic treatment. Taken together, prenatal exposure to PCP produced long-lasting behavioural deficits, accompanied by the abnormal expression and dysfunction of NMDA receptors in postpubertal mice. It is worth investigating the influences of disrupted NMDA receptors during the prenatal period on behaviour in later life.

Morphometrical and morphological analysis of lateral ventricles in schizophrenia patients versus healthy controls

The goal of this report was to highlight lateral ventricle morphology and volume differences between schizophrenia patients and matched controls. Subjects identified as suitable for analysis comprised 15 schizophrenia patients and 15 healthy subjects. The method applied is three-dimensional (3D) volume rendering starting from structural magnetic resonance imaging (MRI) studies of selected ventricular regions. Differences between groups relative to the global ventricular system and its subdivisions were found. Total lateral ventricle volume, right ventricle volume and left ventricle volume were all higher in schizophrenia patients than in controls; unilateral differences between the two groups were also outlined (right ventricle volume>left ventricle volume in schizophrenia patients vs. healthy subjects). Furthermore, occipital and frontal horn enlargement was found in schizophrenia patients compared with normal controls, but the difference in the temporal horn was not statistically significant. A substantial difference was noted in lateral ventricle morphology between the two groups. Our findings were consistent with the literature and may shed light on some of the discrepancies in previous reports on differences in lateral ventricle volume enlargement.

Subcortical alignment precision in patients with schizophrenia

Previous work has demonstrated less accurate alignment of cortical structures for patients with schizophrenia than for matched control subjects when using affine registration techniques. Such a mismatch presents a potential confound for functional neuroimaging studies conducting between-group comparisons. Critically, the same issues may be present for subcortical structures. However, to date no study has explicitly investigated alignment precision for major subcortical structures in patients with schizophrenia. Thus, to address this question we used methods previously validated for assessment of cortical alignment precision to examine alignment precision of subcortical structures. In contrasts to our results with cortex, we found that major subcortical structures (i.e. amygdala, caudate, hippocampus, pallidum, putamen and thalamus) showed similar alignment precision for schizophrenia (N=48) and control subjects (N=45) regardless of the template used (other individuals with schizophrenia or healthy controls). Taken together, the present results show that, unlike cortex, alignment for six major subcortical structures is not compromised in patients with schizophrenia and as such is unlikely to confound between-group functional neuroimaging investigations.

Reduced laterality as a trait marker of schizophrenia--evidence from structural and functional neuroimaging

Laterality is a characteristic principle of the organization of the brain systems for language, and reduced hemispheric asymmetry has been considered a risk factor for schizophrenia. Here we sought support for the risk factor hypothesis by investigating whether reduced asymmetry of temporal lobe structure and function is also present in unaffected relatives. Sixteen schizophrenia patients, 16 age-matched first-degree relatives, and 15 healthy controls underwent high-resolution three-dimensional anatomical imaging and functional magnetic resonance imaging during auditory stimulation. Both the overall auditory cortex and planum temporale volumes and the lateralization to the left hemisphere were markedly reduced in patients. The decrease of lateralization correlated with increased severity of symptoms. In addition, both the overall functional activation in response to auditory stimulation and its asymmetry were reduced in the patients. Relatives had intermediate values between patients and controls on both structural and functional measures. This study provides added support for the idea that reduced hemispheric asymmetry is a biological risk factor for schizophrenia.

White matter connectivity and psychosis in ultra-high-risk subjects: a diffusion tensor fiber tracking study

This study assessed with diffusion tensor imaging (DTI) whether ultra-high-risk subjects who later develop a psychotic disorder (UHR-P) show abnormalities in association white matter fiber tracts as compared to UHR subjects who do not convert to psychosis (UHR-NP) and healthy controls. Participants comprised 17 male UHR subjects and 10 male healthy controls, who received baseline DTI scans before clinical follow-up. The uncinate and arcuate fasciculi, anterior and dorsal cingulate, and subdivisions of the corpus callosum were calculated and visualized, and tract-specific measurements were performed. At 24-month follow-up seven UHR subjects had developed a first psychotic episode. Fractional anisotropy in baseline DTI scans, including left-right asymmetry measures, did not differ between the groups. Thus, DTI measures of these association white matter tracts were not biological markers of psychosis in our UHR sample. Abnormalities of these fiber tracts may develop around or after onset of psychosis. However, further DTI studies in UHR subjects are needed in larger samples.

Attenuated asymmetry of functional connectivity in schizophrenia: a high-resolution EEG study

The interhemispheric asymmetries that originate from connectivity-related structuring of the cortex are compromised in schizophrenia (SZ). Under the assumption that such abnormalities affect functional connectivity, we analyzed its correlate-EEG synchronization-in SZ patients and matched controls. We applied multivariate synchronization measures based on Laplacian EEG and tuned to various spatial scales. Compared to the controls who had rightward asymmetry at a local level (EEG power), rightward anterior and leftward posterior asymmetries at an intraregional level (1st and 2nd order S-estimator), and rightward global asymmetry (hemispheric S-estimator), SZ patients showed generally attenuated asymmetry, the effect being strongest for intraregional synchronization in the alpha and beta bands. The abnormalities of asymmetry increased with the duration of the disease and correlated with the negative symptoms. We discuss the tentative links between these findings and gross anatomical asymmetries, including the cerebral torque and gyrification pattern, in normal subjects and SZ patients.

Evidence from intrinsic activity that asymmetry of the human brain is controlled by multiple factors

Cerebral lateralization is a fundamental property of the human brain and a marker of successful development. Here we provide evidence that multiple mechanisms control asymmetry for distinct brain systems. Using intrinsic activity to measure asymmetry in 300 adults, we mapped the most strongly lateralized brain regions. Both men and women showed strong asymmetries with a significant, but small, group difference. Factor analysis on the asymmetric regions revealed 4 separate factors that each accounted for significant variation across subjects. The factors were associated with brain systems involved in vision, internal thought (the default network), attention, and language. An independent sample of right- and left-handed individuals showed that hand dominance affects brain asymmetry but differentially across the 4 factors supporting their independence. These findings show the feasibility of measuring brain asymmetry using intrinsic activity fluctuations and suggest that multiple genetic or environmental mechanisms control cerebral lateralization.

General absence of abnormal cortical asymmetry in childhood-onset schizophrenia: a longitudinal study

BACKGROUND

Childhood-onset schizophrenia (COS) is a rare, severe form of the adult-onset illness, with more salient neurobiological causes. Previous cross-sectional structural neuroimaging research has suggested that normal cortical asymmetry patterns [(R-L)/(R+L)] may be altered in adult schizophrenia, although these findings were not well replicated. Recent studies show dynamic changes in brain asymmetry during childhood and adolescence. We hypothesized that COS patients would show a lack of normal development of asymmetry and decreased overall asymmetry.

METHODS

Prospective structural magnetic resonance scans were obtained at baseline and at two-year follow-up visits in 49 right-handed COS patients (mean baseline age: 14.72+/-2.63, 117 scans) and 50 age and sex-matched, right-handed healthy controls (mean baseline age: 15.15+/-3.37, 125 scans). Cortical thickness was calculated at 40,962 homologous points across each cerebral hemisphere using a fully automated, validated method. Differences in developmental asymmetry patterns across the cortical surface were analyzed using a linear mixed effects regression model.

RESULTS

No significant asymmetry differences were found either for cross-sectional comparisons of COS and healthy controls across the lateral and medial cortical surfaces or with respect to timing of developmental changes in asymmetry.

CONCLUSIONS

The present findings do not support asymmetry differences for this severe, early form of schizophrenia.

Neuroanatomical asymmetry patterns in individuals with schizophrenia and their non-psychotic siblings

Neuroanatomical endophenotypes may reveal insights into the processes by which genetic factors increase the risk of developing schizophrenia. To determine whether patterns of neuroanatomical asymmetries may be useful as schizophrenia-related endophenotypes, we compared patterns of structural asymmetries in patients with schizophrenia, healthy controls, and their respective siblings. The surfaces of the left and right amygdala, hippocampus, thalamus, caudate nucleus, putamen, globus pallidus, and nucleus accumbens were assessed in 40 pairs of healthy comparison controls (CON) and their siblings (CON-SIB) and 25 pairs of patients with schizophrenia (SCZ) and their siblings (SCZ-SIB) in magnetic resonance (MR) images using large deformation diffeomorphic metric mapping (LDDMM) and parallel transport techniques. The within-subject asymmetry deformation of each structure was first measured via LDDMM, and then translated to a global template via parallel transport for evaluation of the patterns of asymmetry both within and across siblings. Our results revealed that asymmetries observed in CON subjects occurred in the amygdala and the anterior segment of the hippocampus with more pronounced expansion deformation in the right-sided structures (R>L asymmetry) but not in the basal ganglia and thalamus. Disturbance in this pattern of asymmetries was observed in both SCZ and SCZ-SIB subjects. More specifically, exaggerations and reductions in the normative pattern of asymmetries were observed in the amygdala-hippocampus formation, basal ganglia, and thalamus. These altered patterns of asymmetries are present in subjects with schizophrenia and their siblings, and therefore may represent a schizophrenia-related endophenotype.

Workshop on defining the significance of progressive brain change in schizophrenia: December 12, 2008 American College of Neuropsychopharmacology (ACNP) all-day satellite, Scottsdale, Arizona. The rapporteurs' report

In 1990 a satellite session of the American College of Neuropsychopharmacology (ACNP) Annual Meeting was held that focused on the question of whether progressive changes in brain structure occur in schizophrenia and this session raised considerable controversy. Eighteen years later, on December 12, 2008, after much data have since accumulated on this topic, a group of approximately 45 researchers gathered after the annual ACNP meeting to participate in a similar workshop on several unresolved questions still remaining: (1) How strong and consistent is the evidence? (2) Is there anatomic specificity to changes and is it disease specific or subject specific? (3) What is the time course? (4) What is the underlying pathophysiology (i.e. is it central to the disease process or is it due to neuroleptic treatment or other epiphenomena? (5) What is its clinical significance? and (6) Are there treatment implications? The day was chaired by Lynn E. DeLisi and co-chaired by Stephen J. Wood. Christos Pantelis and Jeffrey A. Lieberman extensively helped with its planning. The ACNP assisted in its organization as an official satellite of its annual meeting and several pharmaceutical companies provided support with unrestricted educational grants. The following is a summary of the sessions as recounted by rapporteurs whose job was to record as closely as possible the outcome of discussions on the above outlined questions.