Long-term antipsychotic treatment and brain volumes: a longitudinal study of first-episode schizophrenia

Parietal lobe volume deficits in adolescents with schizophrenia and adolescents with cannabis use disorders

OBJECTIVE

In early-onset schizophrenia (EOS), the earliest structural brain volumetric abnormalities appear in the parietal cortices. Early exposure to cannabis may represent an environmental risk factor for developing schizophrenia. This study characterized cerebral cortical gray matter structure in adolescents in regions of interest (ROIs) that have been implicated in EOS and cannabis use disorders (CUD).

METHOD

T1-weighted magnetic resonance images were acquired from adolescents with EOS (n = 35), CUD (n = 16), EOS + CUD (n = 13), and healthy controls (HC) (n = 51). Using FreeSurfer, brain volume was examined within frontal, temporal, parietal and subcortical ROIs by a 2 (EOS versus no EOS) × 2 (CUD versus no CUD) design using multivariate analysis of covariance. In ROIs in which volumetric differences were identified, additional analyses of cortical thickness and surface area were conducted.

RESULTS

A significant EOS-by-CUD interaction was observed. In the left superior parietal region, both "pure" EOS and "pure" CUD had smaller gray matter volumes that were associated with lower surface area compared with HC. A similar alteration was observed in the comorbid group compared with HC, but there was no additive volumetric deficit found in the comorbid group compared with the separate groups. In the left thalamus, the comorbid group had smaller gray matter volumes compared with the CUD and HC groups.

CONCLUSIONS

These preliminary data indicate that the presence of a CUD may moderate the relationship between EOS and cerebral cortical gray matter structure in the left superior parietal lobe. Future research will follow this cohort over adolescence to further examine the impact of cannabis use on neurodevelopment.

Intact relational memory and normal hippocampal structure in the early stage of psychosis

BACKGROUND

Previous studies indicate that the transition to psychosis is associated with dynamic changes of hippocampal integrity. Here we explored hippocampal volume and neural activation during a relational memory task in patients who were in the early stage of a psychotic illness.

METHODS

Forty-one early psychosis patients and 34 healthy control subjects completed a transitive inference (TI) task used previously in chronic schizophrenia patients. Participants learned to select the "winner" of two sets of stimulus pairs drawn from an overlapping sequence (A > B > C > D > E) and a nonoverlapping set (a > b, c > d, e > f, g > h). During a functional magnetic resonance imaging scan, participants were tested on the trained pairs and made inferential judgments on novel pairings that could be solved based on training (e.g., B vs. D). Hippocampal volumes were manually segmented and compared between groups. Functional magnetic resonance imaging analyses included 27 early psychosis patients and 30 control subjects who met memory training criteria.

RESULTS

Groups did not differ on inference performance or hippocampal volume and exhibited similar activation of medial temporal regions when judging nonoverlapping pairs. However, patients who failed to meet memory training criteria had smaller hippocampal volumes. Neural activity during TI was less widespread in early psychosis patients, but between-group differences were not significant. Hippocampal activity during TI was positively correlated with inference performance only in control subjects.

CONCLUSIONS

Our results provide evidence that relational memory impairment and hippocampal abnormalities, well established in chronic schizophrenia, are not fully present in early psychosis patients. This provides a rationale for early intervention, targeting the possible delay, reduction, or prevention of these deficits.

Association of the ZNF804A gene polymorphism rs1344706 with white matter density changes in Chinese schizophrenia

BACKGROUND

ZNF804A gene polymorphism rs1344706, the first genetic risk variant to achieve genome wide significance for schizophrenia, has been linked to neural functional connectivity. Dysconnectivity of WM may be the primary pathological mechanism of schizophrenia. Association of this variant with regional WM density has not been investigated in schizophrenic patients.

METHODS

69 healthy controls and 80 patients with schizophrenia underwent genotyping of rs1344706 SNPs, and were examined for WM density (T1-weighted MRI). The association of rs1344706 with WM changes in schizophrenia patients and healthy controls was analyzed using a full-factorial 2×2 analysis of variance.

RESULTS

1. There was an interaction on WM density in the left prefrontal lobe between the rs1344706 genotype and schizophrenic diagnosis, where the risk T allele carriers presented higher WM density in the schizophrenia patients and lower WM density in healthy controls in comparison with the non-risk allele carriers. 2. The risk allele was associated with an increased WM density of the bilateral hippocampus in both the patients and the healthy group.

LIMITATION

The influence of antipsychotics to the white matter in schizophrenic patients was not fully eliminated.

CONCLUSIONS

The ZNF804A variant may confer risk for schizophrenia by exerting its effects on the WM in the left prefrontal lobe together with other risk factors for schizophrenia.

Systematic meta-review and quality assessment of the structural brain alterations in schizophrenia

BACKGROUND

The large quantity of systematic reviews of magnetic resonance imaging studies in schizophrenia challenges their meaningful interpretation. This meta-review synthesises the available information from systematic reviews of structural alteration in both chronic and first-episode schizophrenia.

METHODS

Systematic reviews were identified using electronic databases. Review methodological quality was assessed according to the Assessment of Multiple Systematic Reviews checklist. Data were extracted in duplicate and quality assessed for consistency and precision, guided by Grading of Recommendations Assessment, Development and Evaluation recommendations.

RESULTS

Integration of volumetric and voxel-based estimates allowed critical assessment of the magnitude and location of anatomical differences. There is evidence for grey matter reductions of anterior cingulate, frontal (particularly medial and inferior) and temporal lobes, hippocampus/amygdala, thalamus, and insula that may be magnified over time. Other regional alterations appear specific to illness stage or medication status.

CONCLUSIONS

There is limited high quality evidence supporting grey or white matter changes in schizophrenia, which has previously been obscured by a large volume of conflicting lower quality evidence.

Hippocampal shape and volume changes with antipsychotics in early stage psychotic illness

Progression of hippocampal shape and volume abnormalities has been described in psychotic disorders such as schizophrenia. However it is unclear how specific antipsychotic medications influence the development of hippocampal structure. We conducted a longitudinal, randomized, controlled, multisite, double-blind study involving 14 academic medical centers (United States 11, Canada 1, Netherlands 1, and England 1). One hundred thirty-four first-episode psychosis patients (receiving either haloperidol [HAL] or olanzapine [OLZ]) and 51 healthy controls were followed for up to 104 weeks using magnetic resonance imaging and large-deformation high-dimensional brain mapping of the hippocampus. Changes in hippocampal volume and shape metrics (i.e., percentage of negative surface vertex slopes, and surface deformation) were evaluated. Mixed-models analysis did not show a significant group-by-time interaction for hippocampal volume. However, the cumulative distribution function of hippocampal surface vertex slopes showed a notable left shift with HAL treatment compared to OLZ treatment and to controls. OLZ treatment was associated with a significantly lower percentage of "large magnitude" negative surface vertex slopes compared to HAL treatment (p = 0.004). Surface deformation maps however did not localize any hippocampal regions that differentially contracted over time with OLZ treatment, after FDR correction. These results indicate that surface analysis provides supplementary information to volumetry in detecting differential treatment effects of the hippocampus. Our results suggest that OLZ is associated with less longitudinal hippocampal surface deformation than HAL, however the hippocampal regions affected appear to be variable across patients.

Beyond the facts in schizophrenia: closing the gaps in diagnosis, pathophysiology, and treatment

BACKGROUND

Although schizophrenia has been considered a distinct disease entity for the past century, its precise definition and etio-pathophysiology remain obscure and its treatment remains unsatisfactory. In this review, we summarize our state of knowledge about the etiology, pathophysiology, clinical features, and treatment of schizophrenia. METHODOLOGICAL ISSUES: The inadequacy of the major conceptual models of schizophrenia is a major roadblock in providing a coherent explanation for the known facts of this illness, despite these limitations and its changing definitions, the construct of schizophrenia does convey useful information: (i) patients diagnosed as having schizophrenia do have a real disease--they experience both suffering and disability; (ii) a diagnosis of schizophrenia does suggest a distinctive clinical profile--a characteristic long-term course; an admixture of positive, negative, and cognitive symptoms; (iii) a diagnosis of schizophrenia has clear treatment and prognostic implications--likelihood of benefit from antipsychotic treatment and likelihood of incomplete recovery; and (iv) schizophrenia satisfies criteria for a valid diagnostic entity better than almost any other psychiatric diagnosis.

DISCUSSION

On the other hand, the concept of schizophrenia has serious shortcomings. First, it is not a single disease entity--it has multiple etiological factors and pathophysiological mechanisms but common phenotypic features. Second, its clinical manifestations are so diverse that its extreme variability has been considered by some to be a core feature. Third, its boundaries remain ill defined and not clearly demarcated from other clinical entities.

CONCLUSIONS

A necessary next step is to deconstruct schizophrenia as an entity into component dimensions--endophenotypes linked to unique etiological and pathophysiological processes that may yield unique treatment targets. Innovative approaches are needed to elucidate the biological substrates of these entities because such clarity is vital for replicable research. We conclude by identifying the critical gaps in our knowledge, and unmet needs in our approaches to care, and outline steps that can move the field forward.

Olanzapine stimulates proliferation but inhibits differentiation in rat oligodendrocyte precursor cell cultures

In the developing brain, oligodendrocyte progenitor cells (OPCs) proliferate, migrate, and differentiate into mature oligodendrocytes (OLs) capable of myelinating axons. Recently, OPCs have been identified as an abundant and widespread population in the adult as well as in the developing animal. Current research indicates that these OPCs in the adult brain can proliferate and differentiate into myelinating OLs, albeit with different potentialities from those in developing animals. Multiple lines of evidence, from neuroimaging, postmortem, and genetic association studies, have implicated OL and myelin dysfunction in the pathogenesis of schizophrenia. If altered OL function is involved in pathogenesis, OPCs may thus respond to antipsychotic drugs during the recovery process. In the present study, we used primary OPC cultures from optic nerve of newborn Wistar rat pups to investigate the direct effects of haloperidol (HPD; a typical antipsychotic) and olanzapine (OLZ; an atypical antipsychotic) on the proliferation and differentiation of OPCs. Our results showed that 1) OLZ treatment significantly increased the number of viable OPCs when compared to HPD treatment at relatively high concentrations, 2) OLZ treatment suppressed the expression of myelin basic protein (MBP), and to a greater extent than HPD treatment, and 3) these pharmacological effects may be mediated via the ERK signaling pathway. Our findings suggest a glial mechanism for the antipsychotic action of OLZ, and a role for oligodendrocyte-lineage cells in the pathogenesis and treatment of schizophrenia.

Gray matters!--mapping the transition to psychosis

Despite many neuroimaging studies on schizophrenia showing brain abnormalities the exact time course of their occurrence is unknown. Studies of gray matter are a powerful tool in biological psychiatry and provide an unprecedented opportunity for brain structure investigations. Here we compared cross-sectional and longitudinal structural neuroimaging studies distinguishing high-risk subjects developing psychosis from those who did not. These investigations on gray matter volumes in the prodromal phase potentially identify core structural markers of impending psychoses and clarify dynamic changes underlying the transition. Subjects at high risk of psychosis show qualitatively similar albeit less severe gray matter abnormalities as patients with psychosis.

A follow-up MRI study of the fusiform gyrus and middle and inferior temporal gyri in schizophrenia spectrum

While longitudinal magnetic resonance imaging (MRI) studies have demonstrated progressive gray matter reduction of the superior temporal gyrus (STG) during the early phases of schizophrenia, it remains largely unknown whether other temporal lobe structures also exhibit similar progressive changes and whether these changes, if present, are specific to schizophrenia among the spectrum disorders. In this longitudinal MRI study, the gray matter volumes of the fusiform, middle temporal, and inferior temporal gyri were measured at baseline and follow-up scans (mean inter-scan interval=2.7 years) in 18 patients with first-episode schizophrenia, 13 patients with schizotypal disorder, and 20 healthy controls. Both schizophrenia and schizotypal patients had a smaller fusiform gyrus than controls bilaterally at both time points, whereas no group difference was found in the middle and inferior temporal gyri. In the longitudinal comparison, the schizophrenia patients showed significant fusiform gyrus reduction (left, -2.6%/year; right, -2.3%/year) compared with schizotypal patients (left: -0.4%/year; right: -0.2%/year) and controls (left: 0.1%/year; right: 0.0%/year). However, the middle and inferior temporal gyri did not exhibit significant progressive gray matter change in all diagnostic groups. In the schizophrenia patients, a higher cumulative dose of antipsychotics during follow-up was significantly correlated with less severe gray matter reduction in the left fusiform gyrus. The annual gray matter loss of the fusiform gyrus did not correlate with that of the STG previously reported in the same subjects. Our findings suggest regional specificity of the progressive gray matter reduction in the temporal lobe structures, which might be specific to overt schizophrenia within the schizophrenia spectrum.

Aberrations in the arcuate fasciculus are associated with auditory verbal hallucinations in psychotic and in non-psychotic individuals

The pathophysiology of auditory verbal hallucinations (AVH) is still unclear. Cognitive as well as electrophysiological studies indicate that a defect in sensory feedback (corollary discharge) may contribute to the experience of AVH. This could result from disruption of the arcuate fasciculus, the major tract connecting frontal and temporo-parietal language areas. Previous diffusion tensor imaging studies indeed demonstrated abnormalities of this tract in schizophrenia patients with AVH. It is, however, difficult to disentangle specific associations with AVH in this patient group as many other factors, such as other positive and negative symptoms, medication or halted education could likewise have affected tract integrity. We therefore investigated AVH in relative isolation and studied a group of non-psychotic individuals with AVH as well as patients with AVH and non-hallucinating matched controls. We compared tract integrity of the arcuate fasiculus and of three other control tracts, between 35 non-psychotic individuals with AVH, 35 schizophrenia patients with AVH, and 36 controls using diffusion tensor imaging and magnetization transfer imaging. Both groups with AVH showed an increase in magnetization transfer ratio (MTR) in the arcuate fasciculus, but not in the other control tracts. In addition, a general decrease in fractional anisotropy (FA) for almost all bundles was observed in the patient group, but not in the non-psychotic individuals with AVH. As increased MTR in the arcuate fasciculus was present in both hallucinating groups, a specific association with AVH seems plausible. Decreases in FA, on the other hand, seem to be related to other disease processes of schizophrenia.

Understanding aberrant white matter development in schizophrenia: an avenue for therapy?

Although historically gray matter changes have been the focus of neuropathological and neuroradiological studies in schizophrenia, in recent years an increasing body of research has implicated white matter structures and its constituent components (axons, their myelin sheaths and supporting oligodendrocytes). This article summarizes this body of literature, examining neuropathological, neurogenetic and neuroradiological evidence for white matter pathology in schizophrenia. We then look at the possible role that antipsychotic medication may play in these studies, examining both its role as a potential confounder in studies examining neuronal density and brain volume, but also the possible role that these medications may play in promoting myelination through their effects on oligodendrocytes. Finally, the role of potential novel therapies is discussed.

Brain tissue changes and antipsychotic medication

Schizophrenia is associated with progressive brain changes, including progressive brain tissue decreases and lateral ventricular volume increases for up to at least 20 years after disease onset. In view of the fact that the vast majority of such patients are treated with antipsychotic medication and that recent non-human mammalian studies have reported an association between antipsychotic medication and brain tissue changes, the important question arises as to whether the brain changes seen in schizophrenia are associated with antipsychotic medication. The reviewed article presents structural magnetic resonance neuroimaging data relating to 211 patients with schizophrenia from the Iowa Longitudinal Study, which demonstrates that greater intensity of antipsychotic treatment was associated with indicators of generalized and specific brain tissue changes, after controlling for the effects of illness duration, illness severity and substance abuse. The study and its implications are discussed in the context of the current state of knowledge regarding the pathophysiology of schizophrenia.

Duration of untreated illness in schizophrenia is not associated with 5-year brain volume change

OBJECTIVES

Evidence for an association between duration of untreated illness (DUI) with clinical and functional outcome or brain volume (change) in schizophrenia patients is inconclusive. We aimed to investigate the relationship between DUI, outcome and brain volume at illness onset or brain volume change during the first five years of the illness in first-episode patients.

METHODS

Magnetic resonance images were acquired at baseline (T0) and after 5-year (T5) of 57 schizophrenia patients. Correlations were calculated in patients between brain volume (change), DUI and outcome variables.

RESULTS

We found no significant correlation between DUI and brain volume (change) in schizophrenia patients. A longer DUI was significantly correlated with higher PANSS scores at T0 and T5, and with higher scores on the Camberwell Assessment of Need scale at T5. Baseline volume of the cerebrum and lateral ventricles, and cerebellum volume (change) were associated with PANSS scores at T0 and T5.

CONCLUSION

Although clinical outcome is associated with both brain volume (change) and DUI, we found no evidence for a relationship between DUI and brain volume (change). DUI and baseline brain volume or 5-year brain volume (change) seem to explain different parts of the variation in clinical outcome.

Progressive brain change in schizophrenia: a prospective longitudinal study of first-episode schizophrenia

BACKGROUND

Schizophrenia has a characteristic onset during adolescence or young adulthood but also tends to persist throughout life. Structural magnetic resonance studies indicate that brain abnormalities are present at onset, but longitudinal studies to assess neuroprogression have been limited by small samples and short or infrequent follow-up intervals.

METHODS

The Iowa Longitudinal Study is a prospective study of 542 first-episode patients who have been followed up to 18 years. In this report, we focus on those patients (n = 202) and control subjects (n = 125) for whom we have adequate structural magnetic resonance data (n = 952 scans) to provide a relatively definitive determination of whether progressive brain change occurs over a time interval of up to 15 years after intake.

RESULTS

A repeated-measures analysis showed significant age-by-group interaction main effects that represent a significant decrease in multiple gray matter regions (total cerebral, frontal, thalamus), multiple white matter regions (total cerebral, frontal, temporal, parietal), and a corresponding increase in cerebrospinal fluid (lateral ventricles and frontal, temporal, and parietal sulci). These changes were most severe during the early years after onset. They occur at severe levels only in a subset of patients. They are correlated with cognitive impairment but only weakly with other clinical measures.

CONCLUSIONS

Progressive brain change occurs in schizophrenia, affects both gray matter and white matter, is most severe during the early stages of the illness, and occurs only in a subset of patients. Measuring severity of progressive brain change offers a promising new avenue for phenotype definition in genetic studies of schizophrenia.

Putative structural neuroimaging endophenotypes in schizophrenia: a comprehensive review of the current evidence

The genetic contribution to schizophrenia etiopathogenesis is underscored by the fact that the best predictor of developing schizophrenia is having an affected first-degree relative, which increases lifetime risk by tenfold, as well as the observation that when both parents are affected, the risk of schizophrenia increases to approximately 50%, compared with 1% in the general population. The search to elucidate the complex genetic architecture of schizophrenia has employed various approaches, including twin and family studies to examine co-aggregation of brain abnormalities, studies on genetic linkage and studies using genome-wide association to identify genetic variations associated with schizophrenia. ‘Endophenotypes’, or ‘intermediate phenotypes’, are potentially narrower constructs of genetic risk. Hypothetically, they are intermediate in the pathway between genetic variation and clinical phenotypes and can supposedly be implemented to assist in the identification of genetic diathesis for schizophrenia and, possibly, in redefining clinical phenomenology.

Is schizophrenia developmental adaptation to environmental menaces?

Schizophrenia is a devastating mental disorder, with its symptoms typically emerging during late adolescence to young adulthood. In contrast, accumulating evidence suggests that schizophrenia is a developmental disorder in which brain abnormalities may occur even before birth. This has brought the major challenge to explain such discrepancy of brain deficits occurring during prenatal period and emergence of symptoms during adulthood. A number of ideas have been proposed to explain delayed emergence of symptoms at adulthood in relation to maturational processes of various brain systems during adolescence. However, these still lack clear relationship to prenatal deficits. Thus, a key to better understand the pathology of schizophrenia is to unveil a theory or model that can explain the relationship between prenatal deficits and post-pubertal onset of symptoms. Here we propose a novel hypothesis, along with discussion of several lines of evidences supporting it, that schizophrenia may not be a disorder in a strict sense, but rather be understood as the biological state occurring as consequence of adaptation to severe environmental conditions during the prenatal periods, which explains the relationship between prenatal developmental deficits and the postnatal maturational process for onset of symptoms.

Cannabinoid receptor 1 gene polymorphisms and marijuana misuse interactions on white matter and cognitive deficits in schizophrenia

Marijuana exposure during the critical period of adolescent brain maturation may disrupt neuro-modulatory influences of endocannabinoids and increase schizophrenia susceptibility. Cannabinoid receptor 1 (CB1/CNR1) is the principal brain receptor mediating marijuana effects. No study to-date has systematically investigated the impact of CNR1 on quantitative phenotypic features in schizophrenia and inter-relationships with marijuana misuse. We genotyped 235 schizophrenia patients using 12 tag single nucleotide polymorphisms (tSNPs) that account for most of CB1 coding region genetic variability. Patients underwent a high-resolution anatomic brain magnetic resonance scan and cognitive assessment. Almost a quarter of the sample met DSM marijuana abuse (14%) or dependence (8%) criteria. Effects of CNR1 tSNPs and marijuana abuse/dependence on brain volumes and neurocognition were assessed using ANCOVA, including co-morbid alcohol/non-marijuana illicit drug misuse as covariates. Significant main effects of CNR1 tSNPs (rs7766029, rs12720071, and rs9450898) were found in white matter (WM) volumes. Patients with marijuana abuse/dependence had smaller fronto-temporal WM volumes than patients without heavy marijuana use. More interestingly, there were significant rs12720071 genotype-by-marijuana use interaction effects on WM volumes and neurocognitive impairment; suggestive of gene-environment interactions for conferring phenotypic abnormalities in schizophrenia. In this comprehensive evaluation of genetic variants distributed across the CB1 locus, CNR1 genetic polymorphisms were associated with WM brain volume variation among schizophrenia patients. Our findings suggest that heavy cannabis use in the context of specific CNR1 genotypes may contribute to greater WM volume deficits and cognitive impairment, which could in turn increase schizophrenia risk.

Long term antipsychotic treatment does not alter metabolite concentrations in rat striatum: an in vivo magnetic resonance spectroscopy study

Proton magnetic resonance spectroscopy (MRS) studies of schizophrenic patients generally reveal reduced levels of N-acetyl aspartate (NAA) when compared with healthy controls. Whether this reduction is due to the disease or to the drugs used for treatment remains an open question. Numerous human and animal studies have attempted to determine the effects of antipsychotics on NAA levels with mixed results. The majority of the animal studies were ex vivo, which may not accurately reflect the in vivo situation, and limitations of the human studies include previous or concomitant medications or other confounds. To overcome these limitations, we dosed 10 rats/group for six months via drinking water with 0.2 or 2 mg/kg/day haloperidol or 10 or 30 mg/kg/day clozapine. Control rats received unadulterated water. Proton MRS data were collected longitudinally over the six month period from a 64 μL voxel containing primarily the right striatum prior to and monthly during drug administration and used to estimate the concentrations of NAA, creatine, and choline. Ratios of NAA, choline, inositol and glutamate+glutamine to creatine were also calculated. Only the Cho/Cr ratio showed a significant time-by-treatment effect (p=0.0285). These results are in agreement with previous studies of the striatum. However, regional and disease-specific effects remain unresolved.

Age-related increase in the number of oligodendrocytes is dysregulated in schizophrenia and mood disorders

The postnatal maturation of the human prefrontal cortex is associated with substantial increase of number of oligodendrocytes. Previously, we reported decreased numerical density of oligodendrocytes in the prefrontal cortex in schizophrenia and mood disorders. To gain further understanding of the role oligodendrocytes in pathogenesis of schizophrenia and mood disorders, we examined the effect of the age on the number of oligodendrocytes in the prefrontal cortex in schizophrenia, bipolar disorder, and major depressive disorder. We revealed the age-related increase in numerical density of oligodendrocytes in layer VI and adjacent white matter of BA10 and BA 9 in normal controls but not in schizophrenia, bipolar disorder, and major depressive disorder. The absence of normal increase in the number of oligodendrocytes in gray and white matter with age in schizophrenia and mood disorders suggests that age-related process of oligodendrocyte increase is dysregulated in schizophrenia and mood disorders.