Gyral and sulcal cortical thinning in adolescents with first episode early-onset psychosis

Magnetic resonance advanced imaging analysis in adolescents: cortical thickness study to identify attenuated psychosis syndrome

PURPOSE

Psychosis is a symptom common to several mental illnesses and a defining feature of schizophrenia spectrum disorders, whose onset typically occurs in adolescence. Neuroradiological studies have reported evidence of brain structural abnormalities in patients with overt psychosis. However, early identification of brain structural changes in young subjects at risk for developing psychosis (such as those with Attenuated Psychosis Syndrome -APS) is currently lacking.

METHODS

Brain 3D T1-weighted and 64 directions diffusion-weighted images were acquired on 55 help-seeking adolescents (12-17 years old) with psychiatric disorders who referred to our Institute. Patients were divided into three groups: non-APS (n = 20), APS (n = 20), and Early-Onset Psychosis (n = 15). Cortical thickness was calculated from T1w images, and Tract-Based Spatial Statistics analysis was performed to study the distribution of white matter fractional anisotropy and all diffusivity metrics. A thorough neuropsychological test battery was adopted to investigate cognitive performance in several domains.

RESULTS

In patients with Attenuated Psychotic Syndrome, the left superior frontal gyrus was significantly thinner compared to patients with non-APS (p = 0.048), and their right medial orbitofrontal cortex thickness was associated with lower working memory scores (p = 0.0025, r = -0.668 for the working memory index and p = 0.001, r = -0.738 for the digit span). Early-Onset Psychosis patients showed thinner left pars triangularis compared to non-APS individuals (p = 0.024), and their left pars orbitalis was associated with impaired performance at the symbol search test (p = 0.005, r = -0.726). No differences in diffusivity along main tracts were found between sub-groups (p > 0.05).

CONCLUSION

This study showed specific associations between structural imaging features and cognitive performance in patients with APS. Characterizing this disorder using neuroimaging could reveal useful information that may aid in the development and evaluation of preventive strategies in these individuals.

Gene Expressions Preferentially Influence Cortical Thickness of Human Connectome Project Atlas Parcellated Regions in First-Episode Antipsychotic-Naïve Psychoses

Altered gene expressions may mechanistically link genetic factors with brain morphometric alterations. Existing gene expression studies have examined selected morphometric features using low-resolution atlases in medicated schizophrenia. We examined the relationship of gene expression with cortical thickness (CT), surface area (SA), and gray matter volume (GMV) of first-episode antipsychotic-naïve psychosis patients (FEAP = 85) and 81 controls, hypothesizing that gene expressions often associated with psychosis will differentially associate with different morphometric features. We explored such associations among schizophrenia and non-schizophrenia subgroups within FEAP group compared to controls. We mapped 360 Human Connectome Project atlas-based parcellations on brain MRI on to the publicly available brain gene expression data from the Allen Brain Institute collection. Significantly correlated genes were investigated using ingenuity pathway analysis to elucidate molecular pathways. CT but not SA or GMV correlated with expression of 1137 out of 15 633 genes examined controlling for age, sex, and average CT. Among these ≈19%, ≈39%, and 8% of genes were unique to FEAP, schizophrenia, and non-schizophrenia, respectively. Variants of 10 among these 1137 correlated genes previously showed genome-wide-association with schizophrenia. Molecular pathways associated with CT were axonal guidance and sphingosine pathways (common to FEAP and controls), selected inflammation pathways (unique to FEAP), synaptic modulation (unique to schizophrenia), and telomere extension (common to NSZ and healthy controls). We demonstrate that different sets of genes and molecular pathways may preferentially influence CT in different diagnostic groups. Genes with altered expressions correlating with CT and associated pathways may be targets for pathophysiological investigations and novel treatment designs.

Abnormal Brain Structure Morphology in Early-Onset Schizophrenia

With less exposure to environmental and medication influences, individuals with early-onset schizophrenia (EOS) may provide valuable evidence to study the pathogenesis and phenotypic pattern of schizophrenia.T1-weighted magnetic resonance images were collected in 60 individuals with EOS and 40 healthy controls. Voxel-based morphometry and surface-based morphometry analyzes were performed. Gray matter volume, cortical thickness and cortical surface area were compared between the EOS and healthy controls and among schizophrenia subgroups (with or without family history of schizophrenia). Compared with healthy controls, the EOS group had reduced gray matter volume in the bilateral middle temporal gyrus and reduced cortical thickness in several brain regions. The sporadic early onset schizophrenia and the familial early onset schizophrenia showed different brain structure morphology. These findings suggest that abnormal brain structure morphology, especially in the temporal and frontal lobes, may be an important pathophysiological feature of EOS.

Association of altered cortical gyrification and psychopathological symptoms in patients with first-episode drug-naïve schizophrenia

Altered brain gyrification in diverse cortical regions has been reported in patients with schizophrenia, which possibly reflects deviations in early neurodevelopment. The main purpose of this study was to examine the relationship between clinical symptoms and abnormal cortical gyrification in drug-naïve patients with schizophrenia in a Chinese Han population. We calculated the whole-brain cortical gyrification of 41 patients with first-episode drug-naïve schizophrenia and 30 age- and sex-matched healthy controls. The Positive and Negative Syndrome Scale (PANSS) was used to evaluate the psychopathology of patients with schizophrenia. Our results showed that compared to healthy controls, patients had higher cortical gyrification in the left lateral occipital cortex, but lower cortical gyrification in the left transverse temporal cortex. Moreover, the cortical gyrification in the left entorhinal cortex and left fusiform were both positively correlated with the general psychopathology of PANSS. Our findings indicate that abnormal cortical gyrification has occurred in the early stage of schizophrenia, suggesting that abnormal cortical gyrification may play an important role in the pathogenesis and symptomatology of schizophrenia.

The association between body mass index and brain morphology in children: a population-based study

Brain morphology is altered in both anorexia nervosa and obesity. However, it is yet unclear if the relationship between Body Mass Index-Standard Deviation Score (BMI-SDS) and brain morphology exists across the BMI-SDS spectrum, or is present only in the extremes. The study involved 3160 9-to-11 year-old children (50.3% female) who participate in Generation R, a population-based study. Structural MRI scans were obtained from all children and FreeSurfer was used to quantify both global and surface-based measures of gyrification and cortical thickness. Body length and weight were measured to calculate BMI. Dutch growth curves were used to calculate BMI-SDS. BMI-SDS was analyzed continuously and in two categories (median split). The relationship between BMI-SDS (range − 3.82 to 3.31) and gyrification showed an inverted-U shape curve in children with both lower and higher BMI-SDS values having lower gyrification in widespread areas of the brain. BMI-SDS had a positive linear association with cortical thickness in multiple brain regions. This study provides evidence for an association between BMI-SDS and brain morphology in a large sample of children from the general population and suggests that a normal BMI during childhood is important for brain development. Future studies could determine whether lifestyle modifications optimize BMI-SDS result in return to more typical patterns of brain morphology.

Brain structural correlates of functional capacity in first-episode psychosis

Impaired functional capacity is a core feature of schizophrenia and presents even in first-episode psychosis (FEP) patients. Impairments in daily functioning tend to persist despite antipsychotic therapy but their neural basis is less clear. Previous studies suggest that volume loss in frontal cortex might be an important contributor, but findings are inconsistent. We aimed to comprehensively investigate the brain structural correlates of functional capacity in FEP using MRI and a reliable objective measure of functioning [University of California, San Diego Performance-Based Skills Assessment (UPSA)]. In a sample of FEP (n = 39) and a well-matched control group (n = 21), we measured cortical thickness, gray matter volume, and white matter tract integrity (fractional anisotropy, FA) within brain regions implicated by previous work. The FEP group had thinner cortex in various frontal regions and fusiform, and reduced FA in inferior longitudinal fasciculus (ILF). In FEP, poorer functional capacity correlated with reduced superior frontal volume and lower FA in left ILF. Importantly, frontal brain volumes and integrity of the ILF were identified as the structural correlates of functional capacity in FEP, controlling for other relevant factors. These findings enhance mechanistic understanding of functional capacity deficits in schizophrenia by specifying the underlying neural correlates. In future, this could help inform intervention strategies.

Developmental Trajectories of Cortical Thickness in Relation to Schizotypy During Adolescence

Investigating potential gray matter differences in adolescents presenting higher levels of schizotypy personality traits could bring further insights into the development of schizophrenia spectrum disorders. Research has yet to examine the morphological correlates of schizotypy features during adolescence prospectively, and no information is available on the developmental trajectories from adolescence to adulthood. We employed mixed model regression analysis to investigate developmental trajectories of cortical thickness (CT) in relation to schizotypy dimensions in a cohort of 109 adolescents from the general population for whom MRI-scans were acquired over a 5-year period, culminating in a total of 271 scans. Structural data were processed with FreeSurfer software, statistical analyses were conducted using mixed regression models following a ROI-based approach, and schizotypy was assessed with the Schizotypal Personality Questionnaire (SPQ). Accelerated thinning was observed in the posterior cingulate cortex in relation to high levels of positive schizotypy, whereas high levels of disorganized schizotypy were associated with a similar trajectory pattern in the anterior cingulate cortex. The developmental course of CT in the prefrontal, occipital, and cingulate cortices differed between adolescents expressing higher vs lower levels of negative schizotypy. Participants reporting high scores on all schizotypy dimensions were associated with differential trajectories of CT in posterior cingulate cortex and occipital cortex. Consistently with prospective developmental studies of clinical risk conversion, the negative schizotypy dimension appears to constitute the most informative dimension for psychosis-related psychopathology, as its cerebral correlates in adolescents most closely overlap with results found in clinical high risk for psychosis studies.

Cognitive and Clinical Predictors of Prefrontal Cortical Thickness Change Following First-Episode of Psychosis

The association of neuroanatomical progression with cognitive and clinical deterioration after first-episode of psychosis remains uncertain. This longitudinal study aims to assess whether i)impaired executive functioning and emotional intelligence at first presentation are associated with progressive prefrontal and orbitofrontal cortical thinning ii)negative symptom severity is linked to progressive prefrontal cortical thinning. 1.5T MRI images were acquired at baseline and after 3.5 years for 20 individuals with first-episode psychosis and 18 controls. The longitudinal pipeline of Freesurfer was employed to parcellate prefrontal cortex at two time points. Baseline cognitive performance was compared between diagnostic groups using MANCOVA. Partial correlations investigated relationships between cognition and negative symptoms at baseline and cortical thickness change over time. Patients displayed poorer performance than controls at baseline in working memory, reasoning/problem solving and emotional intelligence. In patients, loss of prefrontal and orbitofrontal thickness over time was predicted by impaired working memory and emotional intelligence respectively at baseline. Moreover, exploratory analyses revealed that the worsening of negative symptoms over time was significantly related to prefrontal cortical thinning. Results indicate that specific cognitive deficits at the onset of psychotic illness are markers of progressive neuroanatomical deficits and that worsening of negative symptoms occurs with prefrontal thickness reduction as the illness progresses.

Structural Associations of Cortical Contrast and Thickness in First Episode Psychosis

There is growing evidence that psychosis is characterized by brain network abnormalities. Analyzing morphological abnormalities with T1-weighted structural MRI may be limited in discovering the extent of deviations in cortical associations. We assess whether structural associations of either cortical white-gray contrast (WGC) or cortical thickness (CT) allow for a better understanding of brain structural relationships in first episode of psychosis (FEP) patients. Principal component and structural covariance analyses were applied to WGC and CT derived from T1-weighted MRI for 116 patients and 88 controls, to explore sets of brain regions that showed group differences, and associations with symptom severity and cognitive ability in patients. We focused on 2 principal components: one encompassed primary somatomotor regions, which showed trend-like group differences in WGC, and the second included heteromodal cortices. Patients' component scores were related to general psychopathology for WGC, but not CT. Structural covariance analyses with WGC revealed group differences in pairwise correlations across widespread brain regions, mirroring areas derived from PCA. More group differences were uncovered with WGC compared with CT. WGC holds potential as a proxy measure of myelin from commonly acquired T1-weighted MRI and may be sensitive in detecting systems-level aberrations in early psychosis, and relationships with clinical/cognitive profiles.

Mapping Convergent and Divergent Cortical Thinning Patterns in Patients With Deficit and Nondeficit Schizophrenia

Deficit schizophrenia (DS) is a homogeneous subtype of schizophrenia characterized by primary and enduring negative symptoms. However, the underlying neuroanatomical substrate of DS remains poorly understood. Here, we collected high-resolution structural magnetic resonance images of 115 participants, including 33 DS patients, 41 nondeficit schizophrenia (NDS) patients, and 41 healthy controls (HCs), and calculated the cortical thickness and surface area for statistical comparisons among the 3 groups. Relative to the control group, both the DS and NDS groups exhibited convergent cortical thinning in the bilateral inferior frontal gyri and the left superior temporal gyrus. The cortical thinning in the right inferior frontal cortex in the patient group was significantly positively correlated with declines of cognitive flexibility and visuospatial memory. Importantly, compared to the NDS group, the DS group exhibited a more widespread cortical thinning pattern, with the most significant differences in the left temporo-parietal junction area. For the surface area measurement, no significant group differences were observed. Collectively, these results highlight the convergent and divergent cortical thinning patterns between patients with DS and NDS, which provide critical insights into the neuroanatomical substrate of DS and improve our understanding of the biological mechanism that contributes to the negative symptoms and cognitive impairments in DS.

Reduced Prefrontal Gyrification in Carriers of the Dopamine D4 Receptor 7-Repeat Allele With Attention Deficit/Hyperactivity Disorder: A Preliminary Report

Objective: Structural and functional abnormalities have been noted in the prefrontal cortex of individuals with neurodevelopmental disorders such as attention deficit/hyperactivity disorder (ADHD). Cortical thickness and gyrification, both of which have been reported as abnormal in the prefrontal cortex in ADHD, are thought to be modulated by genetic influences during neural development. This study aimed to investigate the effects of a polymorphism of the dopamine DRD4 gene (the 7-repeat (7R) "risk" allele) on thickness and gyrification as distinct parameters of prefrontal cortical structure in children with ADHD. Method: Structural images and genetic samples were obtained from 49 children aged 9-15 years (25 with ADHD and 24 matched controls), and measures of cortical thickness and gyrification for inferior, middle, and superior frontal cortex were calculated. Results: A significant interaction between diagnosis and genotype on prefrontal gyrification was observed, largely driven by reduced inferior frontal gyrification in patients who carried the DRD4 7R allele. Furthermore, inferior frontal gyrification-but not thickness-related to everyday executive functioning in 7R allele carriers across groups. Conclusions: Prefrontal gyrification is reduced in children with ADHD who also carry the DRD4 7R allele, and it relates to critical functional skills in the executive domain in carriers of the risk allele. More broadly, these effects highlight the importance of considering precise neurodevelopmental mechanisms through which risk alleles influence cortical neurogenesis and migration.

Cortical gyrification in schizophrenia: current perspectives

The cerebral cortex of the human brain has a complex morphological structure consisting of folded or smooth cortical surfaces. These morphological features are referred to as cortical gyrification and are characterized by the gyrification index (GI). A number of cortical gyrification studies have been published using the manual tracing GI, automated GI, and local GI in patients with schizophrenia. In this review, we highlighted abnormal cortical gyrification in patients with schizophrenia, first-episode schizophrenia, siblings of patients, and high-risk and at-risk individuals. Previous researches also indicated that abnormalities in cortical gyrification may underlie the severity of clinical symptoms, neurological soft signs, and executive functions. A substantial body of research has been conducted; however, some researches showed an increased GI, which is called as "hypergyria," and others showed a decreased GI, which is called as "hypogyria." We discussed that different GI methods and a wide variety of characteristics, such as age, sex, stage, and severity of illness, might be important reasons for the conflicting findings. These issues still need to be considered, and future studies should address them.

Cortical folding in post-traumatic stress disorder after motor vehicle accidents: Regional differences in gyrification

AIM

Structural and functional magnetic resonance imaging (MRI) studies have revealed evidence of brain abnormalities in post-traumatic stress disorder (PTSD) patients. Cortical complexity and local gyrification index (lGI) reflect potential biological processes associated with normal or abnormal cognitive functioning. In the current study, lGI was used to explore cortical folding in PTSD patients involved in motor vehicle accidents (MVA).

METHODS

MRI brain scans were acquired from 18 PTSD patients who had suffered MVA at least 6 months previously and 18 healthy control subjects. All MRI images were obtained on a 3-T Siemens MRI machine and the cortical folding was analyzed using the workflow provided by software FreeSurfer. A general FreeSurfer's general linear model was used in the group analysis. In addition, correlation analysis was performed between the average of lGI extracted from the significantly different areas and the data for the clinical scale.

RESULTS

The PTSD patients had significantly greater Clinician-Administered PTSD Scale scores than the control group. The patients showed significantly reduced lGI in the left lateral orbitofrontal cortex, consistent with findings of previous volumetric studies on PTSD. But there were no significant correlations in the left lateral orbitofrontal cortex between Clinician-Administered PTSD Scale scores and lGI.

CONCLUSION

We suggest that abnormal gyrification in PTSD patients can be an important indicator of neurodevelopment deficits and may indeed be a biological marker for PTSD.

Prefrontal Cortical Thickness Deficit in Detoxified Alcohol-dependent Patients

Alcohol dependence is a serious disorder that can be related with a number of potential health-related and social consequences. Cortical thickness measurements would provide important information on the cortical structural alterations in patients with alcohol dependence. Twenty-one patients with alcohol dependence and 22 healthy comparison subjects have been recruited and underwent high-resolution brain magnetic resonance (MR) imaging and clinical assessments. T1-weighted MR images were analyzed using the cortical thickness analysis program. Significantly thinner cortical thickness in patients with alcohol dependence than healthy comparison subjects was noted in the left superior frontal cortical region, correcting for multiple comparisons and adjusting with age and hemispheric average cortical thickness. There was a significant association between thickness in the cluster of the left superior frontal cortex and the duration of alcohol use. The prefrontal cortical region may particularly be vulnerable to chronic alcohol exposure. It is also possible that the pre-existing deficit in this region may have rendered individuals more susceptible to alcohol dependence.

Classification of first-episode psychosis in a large cohort of patients using support vector machine and multiple kernel learning techniques

First episode psychosis (FEP) patients are of particular interest for neuroimaging investigations because of the absence of confounding effects due to medications and chronicity. Nonetheless, imaging data are prone to heterogeneity because for example of age, gender or parameter setting differences. With this work, we wanted to take into account possible nuisance effects of age and gender differences across dataset, not correcting the data as a pre-processing step, but including the effect of nuisance covariates in the classification phase. To this aim, we developed a method which, based on multiple kernel learning (MKL), exploits the effect of these confounding variables with a subject-depending kernel weighting procedure. We applied this method to a dataset of cortical thickness obtained from structural magnetic resonance images (MRI) of 127 FEP patients and 127 healthy controls, who underwent either a 3Tesla (T) or a 1.5T MRI acquisition. We obtained good accuracies, notably better than those obtained with standard SVM or MKL methods, up to more than 80% for frontal and temporal areas. To our best knowledge, this is the largest classification study in FEP population, showing that fronto-temporal cortical thickness can be used as a potential marker to classify patients with psychosis.

Cortical thinning and caudate abnormalities in first episode psychosis and their association with clinical outcome

First episode psychosis (FEP) has been associated with structural brain changes, largely identified by volumetric analyses. Advances in neuroimaging processing have made it possible to measure geometric properties that may identify subtle structural changes not appreciated by a measure of volume alone. In this study we adopt complementary methods of assessing the structural integrity of grey matter in FEP patients and assess whether these relate to patient clinical and functional outcome at 3 year follow-up. 1.5 Tesla T1-weighted Magnetic Resonance (MR) images were acquired for 46 patients experiencing their first episode of psychosis and 46 healthy controls. Cerebral cortical thickness and local gyrification index (LGI) were investigated using FreeSurfer software. Volume and shape of the hippocampus, caudate and lateral ventricles were assessed using manual tracing and spherical harmonics applied for shape description. A cluster of cortical thinning was identified in FEP compared to controls; this was located in the right superior temporal gyrus, sulcus, extended into the middle temporal gyrus (lateral temporal cortex - LTC). Bilateral caudate volumes were significantly lower in FEP relative to controls and the right caudate also displayed regions of shape deflation in the FEP group. No significant structural abnormalities were identified in cortical LGI or hippocampal or lateral ventricle volume/shape. Neither LTC nor caudate abnormalities were related to change in symptom severity or global functioning 3 years later. LTC and caudate abnormalities are present at the first episode of psychosis but do not appear to directly affect clinical or functional outcome.

Local gyrification index in probands with psychotic disorders and their first-degree relatives

BACKGROUND

Psychotic disorders are characterized by aberrant neural connectivity. Alterations in gyrification, the pattern and degree of cortical folding, may be related to the early development of connectivity. Past gyrification studies have relatively small sample sizes, yield mixed results for schizophrenia, and are scant for psychotic bipolar and schizoaffective (SZA) disorders and for relatives of these conditions. Here, we examine gyrification in psychotic disorder patients and their first-degree relatives as a possible endophenotype.

METHODS

Regional local gyrification index (LGI) values, as measured by FreeSurfer software, were compared between 243 control subjects, 388 psychotic disorder probands, and 300 of their first-degree relatives. For patients, LGI values were examined grouped across psychotic diagnoses and then separately for schizophrenia, SZA, and bipolar disorder. Familiality (heritability) values and correlations with clinical measures were also calculated for regional LGI values.

RESULTS

Probands exhibited significant hypogyria compared with control subjects in three brain regions and relatives with Axis II cluster A disorders showed nearly significant hypogyria in these same regions. Local gyrification index values in these locations were significantly heritable and uncorrelated with any clinical measure. Observations of significant hypogyria were most widespread in SZA.

CONCLUSIONS

Psychotic disorders appear to be characterized by significant regionally localized hypogyria, particularly in cingulate cortex. This abnormality may be a structural endophenotype marking risk for psychotic illness and it may help elucidate etiological underpinnings of psychotic disorders.

Reduced brain cortical folding in schizophrenia revealed in two independent samples

The cerebral cortex is highly convoluted, and principal folding patterns are determined early in life. Degree of cortical folding in adult life may index aberrations in brain development. Results from previous studies of cortical folding in schizophrenia are inconsistent. Here we investigated cortical folding patterns in the hitherto largest sample of patients with schizophrenia drawn from two independent cohorts. Magnetic resonance imaging scans were acquired from 207 patients and 206 healthy subjects recruited to two separate research projects in Sweden and Norway. Local gyrification index (lGI) was estimated continuously across the cortex using automated methods. Group differences in lGI were analyzed using general linear models. Patients had lower lGI in three large clusters of the cortex with peak differences found in the left precentral gyrus, right middle temporal gyrus, and right precuneus. Similar, although not completely overlapping results were found when the two cohorts were analyzed separately. There were no significant interaction effects between age and diagnosis and gender and diagnosis. The finding of reduced degree of folding in large regions of the cerebral cortex across two independent samples indicates that reduced gyrification is an inherent feature of the brain pathology in schizophrenia.

Impaired cognitive control mediates the relationship between cortical thickness of the superior frontal gyrus and role functioning in schizophrenia

Structural abnormalities in the lateral prefrontal cortex (LPFC) are well-documented in schizophrenia and recent evidence suggests that these abnormalities relate to functional outcome. Cognitive control mechanisms, reliant on the LPFC, are impaired in schizophrenia and predict functional outcome, thus impaired cognitive control could mediate the relationship between neuroanatomical abnormalities in the LPFC and functional outcome. We used surface-based morphometry to investigate relationships between cortical surface characteristics, cognitive control, and measures of social and role functioning in 26 individuals with schizophrenia and 29 healthy controls. Results demonstrate that schizophrenia participants had thinner cortex in a region of the superior frontal gyrus (BA10). Across all participants, decreased cortical thickness in this region related to decreased cognitive control and decreased role functioning. Moreover, cognitive control fully mediated the relationship between cortical thickness in the superior frontal gyrus and role functioning, indicating that neuroanatomical abnormalities in the LPFC adversely impact role functioning via impaired cognitive control processes.

Brain structural and functional changes in adolescents with psychiatric disorders

During adolescence, hormonal and neurodevelopmental changes geared to ensuring reproduction and achieving independence are very likely mediated by the growth of neural processes, remodeling of synaptic connections, increased myelination in prefrontal areas and maturation of connecting subcortical areas. These processes, greatly accelerated in adolescence, follow an asynchronous pattern in different brain areas. Neuroimaging research using functional and structural magnetic resonance imaging has produced most of the insights regarding brain structural and functional neuropathology in adolescent psychiatric disorders. In schizophrenia, first episodes during adolescence are linked to greater-than-normal losses in gray matter density and white matter integrity and show a divergence of maturational trajectories from normative neural development in a progression similar to that of adult-onset schizophrenia. Anxiety and mood disorders in adolescence have been linked to abnormally increased activity in the amygdala and ventral prefrontal cortical areas, although some data suggest that neural abnormalities in the amygdala and anxiety maybe particularly more frequent in adolescents than in adults. Alcohol misuse in adolescence results in reduced integrity in the white matter and reduced gray matter density that, given the high intensity of adolescent synaptic and myelin remodeling, may result in persistent and profound changes in circuits supporting memory and emotional and appetitive control. The interaction of persistent changes due to prenatal exposure with the contemporaneous expression of genetic factors and disturbing environmental exposure may be an important factor in the appearance of psychiatric disorders in adolescence. Further progress in understanding adolescent psychopathology will require postmortem research of molecular and cellular determinants in the adolescent brain.

Age-related cortical thickness differences in adolescents with early-onset schizophrenia compared with healthy adolescents

The aim of the present study was to investigate the influence of age on cerebral cortical thickness in adolescents with early-onset schizophrenia (EOS) (n=22, aged 12-18 years), as compared to an age-matched healthy control group (n=32). All participants were scanned with magnetic resonance imaging. Whereas in the healthy control group there was a negative association between increasing age and cortical thickness measures in widespread brain regions, including frontal and parietal cortices, the patient group showed no significant effects of age when the groups were studied separately. There was a trend towards an age-by-group effect in the left supramarginal gyrus and the right pre- and postcentral gyri. The between-group statistical analysis indicated similar cortical thickness in the patients as in the healthy controls. There were no significant effects of medication on cortical thickness, nor was there any significant sex-by-group interaction. The results suggest that patients with EOS have a deficiency of the expected cortical thinning to occur during adolescence development. The findings are discussed in context of neurobiological processes known to be involved in brain maturation, including synaptic reorganization, pruning and myelination.

Cortical thickness, surface area, and gyrification abnormalities in children exposed to maltreatment: neural markers of vulnerability?

BACKGROUND

Childhood maltreatment has been shown to significantly elevate the risk of psychiatric disorder. Previous neuroimaging studies of children exposed to maltreatment have reported atypical neural structure in several regions, including the prefrontal cortex and temporal lobes. These studies have exclusively investigated volumetric differences rather than focusing on genetically and developmentally distinct indices of brain structure.

METHODS

Here we used surface-based methods to examine cortical thickness, surface area, and local gyrification in a community sample of children with documented experiences of abuse (n = 22) and a group of carefully matched nonmaltreated peers (n = 21).

RESULTS

Reduced cortical thickness in the maltreated compared with the nonmaltreated group was observed in an extended cluster that incorporated the anterior cingulate, superior frontal gyrus, and orbitofrontal cortex. In addition, reduced cortical surface area was observed within the parcellated regions of the left middle temporal area and lingual gyrus. Local gyrification deficits within the maltreated group were located within two clusters, the lingual gyrus and the insula extending into pars opercularis.

CONCLUSIONS

This is the first time structural abnormalities in the anterior cingulate and lingual gyrus have been detected in children exposed to maltreatment. Surface-based methods seem to capture subtle, previously undetected, morphological abnormalities associated with maltreatment. We suggest that these approaches detect developmental precursors of brain volume differences seen in adults with histories of abuse. Because the reported regions are implicated in several clinical disorders, they might constitute biological markers of vulnerability, linking exposure to early adversity and psychiatric risk.

Effects of eight weeks of atypical antipsychotic treatment on middle frontal thickness in drug-naïve first-episode psychosis patients

Atypical antipsychotic medications generally maintain or increase gray matter amount and functioning. First-episode psychosis patients have lower gray matter volume in the middle frontal gyrus, as well as worse performance on spatial working memory tasks compared to controls. This study investigated the effects of short-term four- and eight-week atypical treatment on middle frontal thickness and spatial working memory in first-episode psychosis patients. Nineteen drug-naïve first-episode psychosis patients treated with risperidone or quetiapine and 26 controls completed structural magnetic resonance imaging, a spatial working memory task, and clinical assessment at three intervals (baseline, four weeks, and eight weeks; all patients and 23 controls completed all three assessments). Caudal and rostral middle frontal thicknesses were measured using the automated program Freesurfer. Positive, negative, and general symptoms of the Positive and Negative Syndrome Scale (PANSS) decreased significantly in patients, with most of the change occurring in the first four weeks of treatment. Patients demonstrated an increase in rostral middle frontal thickness over eight weeks of treatment compared to controls. There was a medium effect size relationship between reduction in negative symptoms at four and eight weeks, and a change in rostral middle frontal thickness over eight weeks. No changes were found in spatial working memory ability. Short-term atypical treatment with risperidone or quetiapine can increase prefrontal cortical thickness in psychosis. These findings are notable given the role of the rostral middle frontal region in cognition and the relationship between better cognitive functioning and better functional outcome in psychosis.

Cortical shape and curvedness analysis of structural deficits in remitting and non-remitting depression

In morphometric neuroimaging studies, the relationship between brain structural changes and the antidepressant treatment response in patients with major depressive disorder has been explored to search depression-trait biomarkers. Although patients were treated with serotonin-related drugs, whether the same treatment resulted in remission and non-remission in depressed patients is currently under investigation. We recruited 25 depressed patients and 25 healthy controls and acquired volumetric magnetic resonance imaging of each participant. We used the shape index and curvedness to classify cortical shapes and quantify shape complexities, respectively, in studying the pharmacological effect on brain morphology. The results showed that different regions of structural abnormalities emerged between remitting and non-remitting patients when contrasted with healthy controls. In addition to comparing structural metrics in each cortical parcellation, similar to the traditional voxel-based morphometric method, we highlighted the importance of structural integrity along the serotonin pathway in response to medication treatment. We discovered that disrupted serotonin-related cortical regions might cause non-remission to antidepressant treatment from a pharmacological perspective. The anomalous areas manifested in non-remitting patients were mainly in the frontolimbic areas, which can be used to differentiate remitting from non-remitting participants before medication treatment. Because non-remission is the failure to respond to treatment with serotonin-related drugs, our method may help clinicians choose appropriate medications for non-remitting patients.

Gyrification of Broca's region is anomalously lateralized at onset of schizophrenia in adolescence and regresses at 2 year follow-up

Gyrification of the human cerebral cortex starts in the foetus and progresses in early infancy; the pattern of folding in later life provides a lead to early developmental aberration. By studying gyrification at illness onset in adolescence we hoped to clarify the pathophysiology of schizophrenia. Here we find 1) an area of hypergyria includes Broca's area and extends into the Sylvian fissure to encroach on the anterior insula in the left hemisphere, and 2) an area of hypogyria in the superior temporal lobe approximates to Wernicke's area but is located in the right hemisphere and encroaches on the posterior insula. In Broca's/anterior insula area, right lateralization was present in healthy controls but patients were left lateralized: at two year follow-up gyrification had decreased in patients while it increased in controls, and the reduction predicted impaired category fluency. Progressive change was unaccompanied by cortical thinning (investigated only in the brain regions showing baseline changes in gyrification) indicating that the disease process affecting these brain regions (insula, inferior frontal and superior temporal) is not primarily degenerative. A deviation in the lateralized development of peri-Sylvian areas for language production and comprehension appears critical to the pathophysiology of schizophrenia and may point to its species-specific origin.

Morphometry of structural disconnectivity indicators in subjects at risk and in age-matched patients with schizophrenia

Structural disconnectivity has been hypothesized as being accountable for the pathophysiology of schizophrenia. Morphometric variables suitable for the empirical study of disconnectivity were studied aiming at the research question whether empirical indicators for disconnectivity are already informative in subjects at risk (SAR) and in young matched patients diagnosed with schizophrenia (SZ). In MRI data of subjects of the two diagnostic groups SZ and SAR, the size of the corpus callosum (CC) as indicator for interhemispherical long distance connections and the gyrification index (GI) as indicator for cortico-cortical connections were analyzed compared to a healthy controls (HC). Each subgroup consists of 21 subjects matched for sex and age. Measurements of the CC and GI were estimated in manually performed tracing procedures. GI data revealed significant differences between the diagnostic groups of both SAR and SZ as compared to HC in the frontal and parietal cortices. Measurements of total CC yielded no significant differences between diagnostic groups. The results are suggestive for impaired cortico-cortical connections as indicated by gyrification changes in SZ and also in SAR, whereas interhemispherical connectivity at the same time appears to be unaffected.

Aberrant cortical gyrification in schizophrenia: a surface-based morphometry study

BACKGROUND

Schizophrenia is considered to be a disorder of cerebral connectivity associated with disturbances of cortical development. Disturbances in connectivity at an early period of cortical maturation can result in widespread defects in gyrification. Investigating the anatomic distribution of gyrification defects can provide important information about neurodevelopment in patients with schizophrenia.

METHODS

We undertook an automated surface-based morphometric assessment of gyrification on 3-dimensionally reconstructed cortical surfaces across multiple vertices that cover the entire cortex. We used a sample from our previous research of 57 patients (50 men) with schizophrenia and 41 controls (39 men) in whom we had tested a specific hypothesis regarding presence of both hypo and hypergyria in the prefrontal cortex using a frontal region-of-interest approach.

RESULTS

Regions with significant reductions in gyrification (hypogyria) were seen predominantly in the left hemisphere, involving the insula and several regions of the multimodal association cortex. Although the prefrontal hypergyria documented earlier did not survive the statistical correction required for a whole brain search (cluster inclusion at p = 0.0001), significant hypergyric frontal clusters emerged when the threshold was lowered (cluster inclusion at p = 0.05). In the insula, a reduction in gyrification was related to reduced cortical thickness in patients with schizophrenia.

LIMITATIONS

We studied a sample of patients taking antipsychotic medications, which could have confounded the results. Our sample was predominantly male, limiting the generalizability of our findings.

CONCLUSION

Our observations suggest that the disturbances in cortical gyrification seen in patients with schizophrenia might be related to a disrupted interaction between the paralimbic and the multimodal association cortex and thus might contribute to the pathogenesis of the illness.

Dissociable morphometric differences of the inferior parietal lobule in schizophrenia

Inferior parietal lobule (IPL) forms an integral part of a critical frontoparietal network, which has been implicated in various clinical symptoms and cognitive deficits seen in schizophrenia. Despite its functional relevance, the relatively few studies that have investigated the structural changes in the IPL report inconsistent findings concerning the nature and localization of these changes. We employed a blinded, automated labelling procedure to measure cortical thickness, surface area and the degree of cortical folding of the two distinct subregions of the IPL (Angular Gyrus and Supramarginal Gyrus) in 57 patients with schizophrenia and 41 controls using high-resolution magnetic resonance imaging. Within the IPL, we observed more pronounced morphological changes in supramarginal gyrus compared to angular gyrus in schizophrenia. While supramarginal gyrus in patients showed reduced gyrification, contracted surface area and thinning, the morphometric changes in angular gyrus were largely confined to a reduction in surface area. Significant hemispheric asymmetry was observed in the gyrification of the supramarginal gyrus. Our findings suggest that in addition to abnormalities in the neurodevelopmental processes that contribute to regional surface area and cortical thickness, a specific defect in cortical folding, especially affecting the left hemisphere, is likely to occur in schizophrenia.

Cortical folding in Broca's area relates to obstetric complications in schizophrenia patients and healthy controls

BACKGROUND

The increased occurrence of obstetric complications (OCs) in patients with schizophrenia suggests that alterations in neurodevelopment may be of importance to the aetiology of the illness. Abnormal cortical folding may reflect subtle deviation from normal neurodevelopment during the foetal or neonatal period. In the present study, we hypothesized that OCs would be related to cortical folding abnormalities in schizophrenia patients corresponding to areas where patients with schizophrenia display altered cortical folding when compared with healthy controls.

METHOD

In total, 54 schizophrenia patients and 54 healthy control subjects underwent clinical examination and magnetic resonance image scanning on a 1.5 T scanner. Information on OCs was collected from original birth records. An automated algorithm was used to calculate a three-dimensional local gyrification index (lGI) at numerous points across the cortical mantle.

RESULTS

In both schizophrenia patients and healthy controls, an increasing number of OCs was significantly related to lower lGI in the left pars triangularis (p<0.0005) in Broca's area. For five other anatomical cortical parcellations in the left hemisphere, a similar trend was demonstrated. No significant relationships between OCs and lGI were found in the right hemisphere and there were no significant case-control differences in lGI.

CONCLUSIONS

The reduced cortical folding in the left pars triangularis, associated with OCs in both patients and control subjects suggests that the cortical effect of OCs is caused by factors shared by schizophrenia patients and healthy controls rather than factors related to schizophrenia alone.

Focal and global brain measurements in siblings of patients with schizophrenia

BACKGROUND

It remains unclear whether structural brain abnormalities in schizophrenia are caused by genetic and/or disease-related factors. Structural brain abnormalities have been found in nonpsychotic first-degree relatives of patients with schizophrenia, but results are inconclusive. This large magnetic resonance imaging study examined brain structures in patients with schizophrenia, their nonpsychotic siblings, and healthy control subjects using global and focal brain measurements.

METHODS

From 155 patients with schizophrenia, their 186 nonpsychotic siblings, and 122 healthy controls (including 25 sibling pairs), whole-brain scans were obtained. Segmentations of total brain, gray matter (GM), and white matter of the cerebrum, lateral and third ventricle, and cerebellum volumes were obtained. For each subject, measures of cortical thickness and GM density maps were estimated. Group differences in volumes, cortical thickness, and GM density were analyzed using Structural Equation Modeling, hence controlling for familial dependency of the data.

RESULTS

Patients with schizophrenia, but not their nonpsychotic siblings, showed volumetric differences, cortical thinning, and reduced GM density as compared with control subjects.

CONCLUSIONS

This study did not reveal structural brain abnormalities in nonpsychotic siblings of patients with schizophrenia compared with healthy control subjects using multiple imaging methods. Therefore, the structural brain abnormalities observed in patients with schizophrenia are for the largest part explained by disease-related factors.

The neurodynamic organization of modality-dependent hallucinations

The pathophysiology of hallucinations remains mysterious. This research aims to specifically explore the interaction between hallucinations and spontaneous resting-state activity. We used multimodal magnetic resonance imaging during hallucinations occurrence in 20 drug-free adolescents with a "brief psychotic disorder." They were furthermore compared with 20 matched controls at rest or during exteroceptive stimuli. Anatomical and functional symptom-mapping demonstrated reduced cortical thickness and increased blood oxygen level-dependent signal in modality-dependent association sensory cortices during auditory, visual, and multisensory hallucinations. On the contrary, primary-sensory-cortex recruitment was not systematic and was shown to be associated with increased vividness of the hallucinatory experiences. Spatiotemporal activity patterns in the default-mode network (DMN) during hallucinations and symptom-free periods in patients were compared with patterns measured in healthy individuals. A disengagement of the DMN was concomitant to hallucinations, as for exogenous stimulations in healthy participants. Specifically, spatial and temporal instabilities of the DMN correlated with the severity of hallucinations but persisted during symptom-free periods. These results suggest that hallucinatory experiences emerge from a spontaneous DMN withdrawal, providing a convincing model for hallucinations beyond the auditory modality.

A library of cortical morphology analysis tools to study development, aging and genetics of cerebral cortex

Sharing of analysis techniques and tools is among the main driving forces of modern neuroscience. We describe a library of tools developed to quantify global and regional differences in cortical anatomy in high resolution structural MR images. This library is distributed as a plug-in application for popular structural analysis software, BrainVisa (BV). It contains tools to measure global and regional gyrification, gray matter thickness and sulcal and gyral white matter spans. We provide a description of each tool and examples for several case studies to demonstrate their use. These examples show how the BV library was used to study cortical folding process during antenatal development and recapitulation of this process during cerebral aging. Further, the BV library was used to perform translation research in humans and non-human primates on the genetics of cerebral gyrification. This library, including source code and self-contained binaries for popular computer platforms, is available from the NIH-Neuroimaging Informatics Tools and Resources Clearinghouse (NITRC) resource ( http://www.nitrc.org/projects/brainvisa_ext ).

Reduced cortical thickness in children with new-onset seizures

BACKGROUND AND PURPOSE

Children with new-onset seizures may have antecedent neurobiologic alterations that predispose them to developing seizures. Our aim was to evaluate hippocampal and thalamic volumes and lobar cortical thickness of children with new-onset seizures.

MATERIALS AND METHODS

Twenty-nine children with new-onset seizures and normal MR imaging findings were recruited. Ten patients had generalized seizures, 19 had partial seizures, and 15 were on antiepileptic medications. Twenty-three age-matched healthy controls were also recruited. Hippocampal and thalamic volumes and lobar cortical thickness, including frontal, medial temporal, lateral temporal, parietal, cingulate, and occipital cortical thickness, were assessed by using volumetric T1-weighted imaging and were compared between patients and controls.

RESULTS

There were no significant differences in hippocampal and thalamic volumes of patients with new-onset seizures, including the subgroups with generalized and partial seizures and those on and off antiepileptic medications, compared with controls (P > .01). There was significant reduction in cortical thickness in right cingulate (P = .004), right medial temporal (P = .006), and left frontal (P = .007) cortices in patients with new-onset seizures. Patients with generalized seizures did not demonstrate a significant reduction in cortical thickness (P > .01). Patients with partial seizures demonstrated a significant reduction in cortical thickness in the right frontal (P = .008), right parietal (P = .003), and left frontal (P = .007) cortices. There were no significant differences in cortical thickness among patients on or off antiepileptic medications (P > .01).

CONCLUSIONS

We found reduced cortical thickness in children with new-onset seizures. Further studies are necessary to elucidate the neurobiologic relevance of these structural changes.

Differential effects of surface area, gyrification and cortical thickness on voxel based morphometric deficits in schizophrenia

Voxel Based Morphometry (VBM) and Surface Based Morphometry (SBM) are the two most commonly used methods to study the structure of gray matter in various disease states such as schizophrenia. Though overlapping changes have been observed in same datasets using the two procedures, the proportional contribution of the anatomical properties of the cortical mantle such as thickness, surface area and gyrification to the group differences in gray matter volume (GMV) observed using VBM is unknown. In the present study, we investigate the relationship between the GMV and the anatomical properties of the cortical mantle in regions showing significant VBM changes in schizophrenia using a sample of 57 patients and 41 healthy controls. To this end, we obtained significant clusters showing VBM changes in schizophrenia and studied the contribution of the three anatomical properties derived from SBM to the observed group differences in the GMV using a multiple mediation analysis. Our results suggest that while SBM measures make distinct but regionally variable contribution to the VBM differences, a large proportion of the group difference observed using VBM is not explained by the individual surface anatomical properties. While VBM may be more sensitive in identifying the regions with gray matter abnormalities, studies investigating the pathophysiology of illnesses such as schizophrenia are better informed when both SBM and VBM analyses are performed concurrently.

Imaging derived cortical thickness reduction in high-functioning autism: key regions and temporal slope

Cortical thickness (CT) changes possibly contribute to the complex symptomatology of autism. The aberrant developmental trajectories underlying such differences in certain brain regions and their continuation in adulthood are a matter of intense debate. We studied 28 adults with high-functioning autism (HFA) and 28 control subjects matched for age, gender, IQ and handedness. A surface-based whole brain analysis utilizing FreeSurfer was employed to detect CT differences between the two diagnostic groups and to investigate the time course of age-related changes. Direct comparison with control subjects revealed thinner cortex in HFA in the posterior superior temporal sulcus (pSTS) of the left hemisphere. Considering the time course of CT development we found clusters around the pSTS and cuneus in the left and the paracentral lobule in the right hemisphere to be thinner in HFA with comparable age-related slopes in patients and controls. Conversely, we found clusters around the supramarginal gyrus and inferior parietal lobule (IPL) in the left and the precentral and postcentral gyrus in the right hemisphere to be thinner in HFA, but with different age-related slopes in patients and controls. In the latter regions CT showed a steady decrease in controls but no analogous thinning in HFA. CT analyses contribute in characterizing neuroanatomical correlates of HFA. Reduced CT is present in brain regions involved in social cognition. Furthermore, our results demonstrate that aberrant brain development leading to such differences is proceeding throughout adulthood. Discrepancies in prior morphometric studies may be induced by the complex time course of cortical changes.

Folding of the prefrontal cortex in schizophrenia: regional differences in gyrification

BACKGROUND

Anatomy of prefrontal cortex in schizophrenia has been studied previously by quantifying the degree of gyrification. Conflicting results exist, with some studies showing hypergyria and others showing hypogyria. It is likely that regional variations in cortical folding exist within the prefrontal cortex that could be explored by studying the anatomical subdivisions formed by the sulci and gyri. With surface reconstructions from magnetic resonance imaging, we studied the gyrification within anatomically meaningful subdivisions of prefrontal cortex in schizophrenia.

METHODS

Prefrontal cortex was studied with an automated method to obtain Local Gyrification Index, reflecting the degree of cortical folding in 57 patients with schizophrenia and 42 control subjects. Regional differences within prefrontal cortex were compared between the two groups with a sulcogyral atlas. Effects of hemisphere and age were subsequently assessed.

RESULTS

Patients with schizophrenia had significant hypogyria in most prefrontal regions except the frontomarginal region, which showed hypergyria. The normal left > right pattern of prefrontal gyrification was reversed in schizophrenia. Patients with schizophrenia also showed significant age-related reduction in gyrification at the hypogyric regions.

CONCLUSIONS

The differences between reported findings regarding prefrontal gyrification might reflect regional variation in the nature of the abnormal process of gyrification in schizophrenia. Prefrontal gyrification is significantly influenced by age in schizophrenia, in addition to the influence of neurodevelopmental factors.

Preterm birth and maternal responsiveness during childhood are associated with brain morphology in adolescence

Although supportive parenting has been shown to have positive effects on development, the neurobiological basis of supportive parenting has not been investigated. Thirty-three adolescents were systemically selected from a longitudinal study on child development based on maternal responsiveness during childhood, a measure of supportive parenting, and whether they were born term or preterm. We analyzed the effect of preterm birth on hemispheric and regional (frontal, temporal, parietal) cortical thickness and surface area using mixed-model analysis while also considering the effect of brain hemisphere (left vs. right). We then determined whether these factors were moderated by maternal responsiveness during childhood. Preterm birth was associated with regional and hemispheric differences in cortical thickness and surface area. Maternal responsiveness during childhood moderated hemispheric cortical thickness. Adolescence with mothers that were inconsistently responsive during childhood demonstrated greater overall cortical thickness and greater asymmetry in cortical thickness during adolescence as compared to adolescence with mothers who were consistently responsive or unresponsive during childhood. Maternal responsiveness and preterm birth did not interact. These data suggest that changes in brain morphology associated with preterm birth continue into adolescence and support the notion that the style of maternal-child interactions during childhood influence brain development into adolescence.

Changes in the frontotemporal cortex and cognitive correlates in first-episode psychosis

BACKGROUND

Loss of cortical volume in frontotemporal regions has been reported in patients with schizophrenia and their relatives. Cortical area and thickness are determined by different genetic processes, and measuring these parameters separately may clarify disturbances in corticogenesis relevant to schizophrenia. Our study also explored clinical and cognitive correlates of these parameters.

METHODS

Thirty-seven patients with first-episode psychosis (34 schizophrenia, 3 schizoaffective disorder) and 38 healthy control subjects matched for age and sex took part in the study. Imaging was performed on an magnetic resonance imaging 1.5-T scanner. Area and thickness of the frontotemporal cortex were measured using a surface-based morphometry method (Freesurfer). All subjects underwent neuropsychologic testing that included measures of premorbid and current IQ, working and verbal memory, and executive function.

RESULTS

Reductions in cortical area, more marked in the temporal cortex, were present in patients. Overall frontotemporal cortical thickness did not differ between groups, although regional thinning of the right superior temporal region was observed in patients. There was a significant association of both premorbid IQ and IQ at disease onset with area, but not thickness, of the frontotemporal cortex, and working memory span was associated with area of the frontal cortex. These associations remained significant when only patients with schizophrenia were considered.

CONCLUSIONS

Our results suggest an early disruption of corticogenesis in schizophrenia, although the effect of subsequent environmental factors cannot be excluded. In addition, cortical abnormalities are subject to regional variations and differ from those present in neurodegenerative diseases.

N-methyl-D-aspartate antibody encephalitis: temporal progression of clinical and paraclinical observations in a predominantly non-paraneoplastic disorder of both sexes

Antibodies to the N-methyl-d-aspartate subtype of glutamate receptor have been associated with a newly-described encephalopathy that has been mainly identified in young females with ovarian tumours. However, the full clinical spectrum and treatment responses are not yet clear. We established a sensitive cell-based assay for detection of N-methyl-d-aspartate receptor antibodies in serum or cerebrospinal fluid, and a quantitative fluorescent immunoprecipitation assay for serial studies. Although there was marked intrathecal synthesis of N-methyl-d-aspartate receptor antibodies, the absolute levels of N-methyl-d-aspartate receptor antibodies were higher in serum than in cerebrospinal fluid. N-methyl-d-aspartate receptor antibodies were of the immunoglobulin G1 subclass and were able to activate complement on N-methyl d-aspartate receptor-expressing human embryonic kidney cells. From questionnaires returned on 44 N-methyl-d-aspartate receptor antibody-positive patients, we identified a high proportion without a detected tumour (35/44, 80%: follow-up 3.6–121 months, median 16 months). Among the latter were 15 adult females (43%), 10 adult males (29%) and 10 children (29%), with four in the first decade of life. Overall, there was a high proportion (29%) of non-Caucasians. Good clinical outcomes, as defined by reductions in modified Rankin scores, correlated with decreased N-methyl-d-aspartate receptor antibody levels and were associated with early (<40 days) administration of immunotherapies in non-paraneoplastic patients (P < 0.0001) and earlier tumour removal in paraneoplastic patients (P = 0.02). Ten patients (23%) who were first diagnosed during relapses had no evidence of tumours but had received minimal or no immunotherapy during earlier episodes. Temporal analysis of the onset of the neurological features suggested progression through two main stages. The time of onset of the early features, characterized by neuropsychiatric symptoms and seizures preceded by a median of 10–20 days, the onset of movement disorders, reduction in consciousness and dysautonomia. This temporal dichotomy was also seen in the timing of cerebrospinal fluid, electroencephalographic and in the rather infrequent cerebral imaging changes. Overall, our data support a model in which the early features are associated with cerebrospinal fluid lymphocytosis, and the later features with appearance of oligoclonal bands. The immunological events and neuronal mechanisms underlying these observations need to be explored further, but one possibility is that the early stage represents diffusion of serum antibodies into the cortical grey matter, whereas the later stage results from secondary expansion of the immunological repertoire within the intrathecal compartment acting on subcortical neurons. Four patients, who only had temporal lobe epilepsy without oligoclonal bands, may represent restriction to the first stage.