Reduced N-acetylaspartate in the temporal cortex of rats reared in isolation

Intermittent fasting alleviates type 1 diabetes-induced cognitive dysfunction by improving the frontal cortical metabolic disorder

Intermittent fasting (IF) is an ecological strategy to control various metabolic disorder symptoms, but its protective effect on type 1 diabetes (T1D)-induced cognitive dysfunction and the underlying mechanisms remain poorly defined. Herein, we examined the efficacy of IF in altering the behaviors and brain metabolome in T1D mice and investigated the potential molecular mechanisms. We demonstrated that IF remarkably improved frontal cortical-dependent memory in T1D mice and reduced the loss of neuronal cells. Metabolomics and targeted mass spectrometry assay showed that IF reprogrammed the frontal cortical metabolome composition, including activated the aspartate and glutamate pathway and reversed glycerophospholipid and sphingolipid depositions in T1D mice. Mechanistically, IF attenuated the levels of oxidative stress proteins, such as NOX2, NOX4, 8-OHdG, 4-HNE, and inhibited the levels of pro-apoptotic factors Bax and cleaved Caspase-3, finally improved the memory ability of T1D mice. In vitro studies confirmed the protective effect of the supplemented N-acetylaspartate, a pivotal metabolite involved in IF-regulated T1D-induced cognitive dysfunction, in high glucose-stimulated SH-SY5Y cells by eliminating toxic lipids accumulation, oxidative stress and apoptosis. To conclude, the frontal cortical metabolites mediated the protective effects of IF against T1D-induced cognitive dysfunction by attenuating oxidative stress and apoptotic signaling. Thus, IF can be a potential therapeutic strategy for T1D-induced cognitive dysfunction.

The prefrontal cortex as a target for atypical antipsychotics in schizophrenia, lessons of neurodevelopmental animal models

Prefrontal cortex (PFC) inflammatory imbalance, oxidative/nitrosative stress (O/NS) and impaired neuroplasticity in schizophrenia are thought to have neurodevelopmental origins. Animal models are not only useful to test this hypothesis, they are also effective to establish a relationship among brain disturbances and behavior with the atypical antipsychotics (AAPs) effects. Here we review data of PFC post-mortem and in vivo neuroimaging, human induced pluripotent stem cells (hiPSC), and peripheral blood studies of inflammatory, O/NS, and neuroplasticity alterations in the disease as well as about their modulation by AAPs. Moreover, we reviewed the PFC alterations and the AAP mechanisms beyond their canonical antipsychotic action in four neurodevelopmental animal models relevant to the study of schizophrenia with a distinct approach in the generation of schizophrenia-like phenotypes, but all converge in O/NS and altered neuroplasticity in the PFC. These animal models not only reinforce the neurodevelopmental risk factor model of schizophrenia but also arouse some novel potential therapeutic targets for the disease including the reestablishment of the antioxidant response by the perineuronal nets (PNNs) and the nuclear factor erythroid 2-related factor (Nrf2) pathway, as well as the dendritic spine dynamics in the PFC pyramidal cells.

Enhancement of Aggression Induced by Isolation Rearing is Associated with a Lack of Central Serotonin

Isolation rearing (IR) enhances aggressive behavior, and the central serotonin (5-hydroxytryptamine, 5-HT) system has been linked to IR-induced aggression. However, whether the alteration of central serotonin is the cause or consequence of enhanced aggression is still unknown. In the present study, using mice deficient in central serotonin Tph2^-/- and Lmx1b^-/-, we examined the association between central serotonin and aggression with or without social isolation. We demonstrated that central serotonergic neurons are critical for the enhanced aggression after IR. 5-HT depletion in wild-type mice increased aggression. On the other hand, application of 5-HT in Lmx1b^-/- mice inhibited the enhancement of aggression under social isolation conditions. Dopamine was downregulated in Lmx1b^-/- mice. Similar to 5-HT, L-DOPA decreased aggression in Lmx1b^-/- mice. Our results link the serotoninergic system directly to aggression and this may have clinical implications for aggression-related human conditions.

Stabilized Low-n Amyloid-β Oligomers Induce Robust Novel Object Recognition Deficits Associated with Inflammatory, Synaptic, and GABAergic Dysfunction in the Rat

BACKGROUND

With current treatments for Alzheimer's disease (AD) only providing temporary symptomatic benefits, disease modifying drugs are urgently required. This approach relies on improved understanding of the early pathophysiology of AD. A new hypothesis has emerged, in which early memory loss is considered a synapse failure caused by soluble amyloid-β oligomers (Aβo). These small soluble Aβo, which precede the formation of larger fibrillar assemblies, may be the main cause of early AD pathologies.

OBJECTIVE

The aim of the current study was to investigate the effect of acute administration of stabilized low-n amyloid-β1-42 oligomers (Aβo1-42) on cognitive, inflammatory, synaptic, and neuronal markers in the rat.

METHODS

Female and male Lister Hooded rats received acute intracerebroventricular (ICV) administration of either vehicle or 5 nmol of Aβo1-42 (10μL). Cognition was assessed in the novel object recognition (NOR) paradigm at different time points. Levels of inflammatory (IL-1β, IL-6, TNF-α), synaptic (PSD-95, SNAP-25), and neuronal (n-acetylaspartate, parvalbumin-positive cells) markers were investigated in different brain regions (prefrontal and frontal cortex, striatum, dorsal and ventral hippocampus).

RESULTS

Acute ICV administration of Aβo1-42 induced robust and enduring NOR deficits. These deficits were reversed by acute administration of donepezil and rolipram but not risperidone. Postmortem analysis revealed an increase in inflammatory markers, a decrease in synaptic markers and parvalbumin containing interneurons in the frontal cortex, with no evidence of widespread neuronal loss.

CONCLUSION

Taken together the results suggest that acute administration of soluble low-n Aβo may be a useful model to study the early mechanisms involved in AD and provide us with a platform for testing novel therapeutic approaches that target the early underlying synaptic pathology.

Prolonged Periods of Social Isolation From Weaning Reduce the Anti-inflammatory Cytokine IL-10 in Blood and Brain

Life stressors during critical periods are reported to trigger an immune dysfunction characterised by abnormal production of inflammatory cytokines. Despite the relationship between early stressors and schizophrenia is described, the evidence on inflammatory biomarkers remains limited. We aimed to investigate whether an imbalance between pro- and anti-inflammatory cytokines in the brain is reflected in the peripheral blood of rats submitted to post-weaning social isolation (pwSI), a model with validity to study schizophrenia. We evaluated pro- and anti-inflammatory cytokines (IL-6, TNF-α, and IL-10) simultaneously at blood, prefrontal cortex and hippocampal tissues (Milliplex MAP), including the respective cytokines gene expression (mRNA) (qRT-PCR TaqMan mastermix). We also performed a correlation matrix to explore significant correlations among cytokines (protein and mRNA) in blood and brain, as well as cytokines and total number of square crossings in the open field for isolated-reared animals. Male Wistar rats (n = 10/group) were kept isolated (n = 1/cage) or grouped (n = 3–4/cage) since weaning for 10 weeks. After this period, rats were assessed for locomotion and sacrificed for blood and brain cytokines measurements. Prolonged pwSI decreased IL-10 protein and mRNA in the blood, and IL-10 protein in the hippocampus, along with decreased IL-6 and its mRNA expression in the prefrontal cortex. Our results also showed that cytokines tend to correlate to one-another among the compartments investigated, although blood and brain correlations are far from perfect. IL-10 hippocampal levels were negatively correlated with hyperlocomotion in the open field. Despite the unexpected decrease in IL-6 and unchanged TNF-α levels contrast to the expected pro-inflammatory phenotype, this may suggest that reduced anti-inflammatory signalling may be critical for eliciting abnormal behaviour in adulthood. Altogether, these results suggest that prolonged early-life adverse events reduce the ability to build proper anti-inflammatory cytokine that is translated from blood-to-brain.

Neurobiology and consequences of social isolation stress in animal model-A comprehensive review

The brain is a vital organ, susceptible to alterations under genetic influences and environmental experiences. Social isolation (SI) acts as a stressor which results in alterations in reactivity to stress, social behavior, function of neurochemical and neuroendocrine system, physiological, anatomical and behavioral changes in both animal and humans. During early stages of life, acute or chronic SIS has been proposed to show signs and symptoms of psychiatric and neurological disorders such as anxiety, depression, schizophrenia, epilepsy and memory loss. Exposure to social isolation stress induces a variety of endocrinological changes including the activation of hypothalamic-pituitary-adrenal (HPA) axis, culminating in the release of glucocorticoids (GCs), release of catecholamines, activation of the sympatho-adrenomedullary system, release of Oxytocin and vasopressin. In several regions of the central nervous system (CNS), SIS alters the level of neurotransmitter such as dopamine, serotonin, gamma aminobutyric acid (GABA), glutamate, nitrergic system and adrenaline as well as leads to alteration in receptor sensitivity of N-methyl-D-aspartate (NMDA) and opioid system. A change in the function of oxidative and nitrosative stress (O&NS) mediated mitochondrial dysfunction, inflammatory factors, neurotrophins and neurotrophicfactors (NTFs), early growth response transcription factor genes (Egr) and C-Fos expression are also involved as a pathophysiological consequences of SIS which induce neurological and psychiatric disorders.

A Review of Biomarkers in Mood and Psychotic Disorders: A Dissection of Clinical vs. Preclinical Correlates

Despite significant research efforts aimed at understanding the neurobiological underpinnings of mood (depression, bipolar disorder) and psychotic disorders, the diagnosis and evaluation of treatment of these disorders are still based solely on relatively subjective assessment of symptoms as well as psychometric evaluations. Therefore, biological markers aimed at improving the current classification of psychotic and mood-related disorders, and that will enable patients to be stratified on a biological basis into more homogeneous clinically distinct subgroups, are urgently needed. The attainment of this goal can be facilitated by identifying biomarkers that accurately reflect pathophysiologic processes in these disorders. This review postulates that the field of psychotic and mood disorder research has advanced sufficiently to develop biochemical hypotheses of the etiopathology of the particular illness and to target the same for more effective disease modifying therapy. This implies that a "one-size fits all" paradigm in the treatment of psychotic and mood disorders is not a viable approach, but that a customized regime based on individual biological abnormalities would pave the way forward to more effective treatment. In reviewing the clinical and preclinical literature, this paper discusses the most highly regarded pathophysiologic processes in mood and psychotic disorders, thereby providing a scaffold for the selection of suitable biomarkers for future studies in this field, to develope biomarker panels, as well as to improve diagnosis and to customize treatment regimens for better therapeutic outcomes.

Tianeptine reverses stress-induced asymmetrical hippocampal volume and N-acetylaspartate loss in rats: an in vivo study

Stress-induced hippocampal volume loss and decrease in N-acetylaspartate (NAA) level have been reported to be associated with impaired neural plasticity and neuronal damage in adults. Accordingly, reversing structural and metabolite damage in the hippocampus may be a desirable goal for antidepressant therapy. The present study investigated the effects of tianeptine on chronic stress-induced hippocampal volume loss and metabolite alterations in vivo in 24 Sprague-Dawley rats. Rats were subjected to a consecutive 28-day forced swimming test stress. Tianeptine (50mg/kg) or saline was administered intragastrically 4h after swimming each day. Spontaneous behaviors, serum corticosterone concentration, hippocampal volume and NAA level were evaluated after stress. Chronic tianeptine treatment counteracted the chronic stress-induced suppression of spontaneous behaviors, elevated serum corticosterone concentration, reduced hippocampal volume and decreased NAA level. Moreover, we found asymmetrical right-left hippocampal volume loss in stressed rats, with the left hippocampus more sensitive to chronic stress than the right hippocampus. In addition, stressed rats showed a decreased level of hippocampal metabolites, without significant loss of hippocampal volume. These findings provide experimental evidence for impaired structural plasticity of the brain being an important feature of depressive illness and suggest that prophylactic tianeptine treatments could reverse structural changes in brain. The structural and neurochemical alterations in the hippocampus may be valuable indexes for evaluating the prophylactic and curative effect of antidepressant treatments in depressive and stress-related disorders.

Integrative circuit models and their implications for the pathophysiologies and treatments of the schizophrenias

A preponderance of evidence indicates that the heterogeneous group of schizophrenias is accompanied by disturbances in neural elements distributed throughout multiple levels of interconnected cortico-striato-pallido-thalamic circuitry. These disturbances include a substantial loss of, or failure to develop, both cells and/or appropriate cellular connections in regions that include at least portions of the hippocampus, parahippocampal gyrus, entorhinal cortex, amygdala, prefrontal and anterior cingulate cortex, superior and transverse temporal gyri, and mediodorsal, anterior, and pulvinar nuclei of the thalamus; they appear to reflect failures of early brain maturation, that become codified into dysfunctional circuit properties, that in the opinion of this author cannot be "undone" or even predictably remediated in any physiological manner by existing pharmacotherapies. These circuit disturbances are variable across individuals with schizophrenia, perhaps reflecting the interaction of multiple different risk genes and multiple different epigenetic events. Evidence for these complex circuit disturbances has significant implications for many areas of schizophrenia research, and for future efforts toward developing more effective therapeutic approaches for this group of disorders. The conclusion of this chapter is that such future efforts should focus on further developing and refining medications that target nodal or convergent circuit points within the limbic-motor interface, with the goal of constraining the scope and severity of psychotic exacerbations, to be used in concert with systematic rehabilitative psychotherapies designed to engage healthy neural systems to compensate for and replace dysfunctional higher circuit elements. This strategy should be applied in both preventative and treatment settings, and disseminated for community delivery via an evidence-based manualized format. In contrast to alternative treatment strategies that range from complex polypharmacy to gene therapies to psychosurgical interventions, the use of combined medication plus targeted cognitive and behavioral psychotherapy has both common sense and time-tested documented efficacy with numerous other neuropsychiatric disorders.

Differential regional N-acetylaspartate deficits in postmortem brain in schizophrenia, bipolar disorder and major depressive disorder

There is substantial evidence for the involvement of the hippocampus and subcortical regions in the neuropathology of schizophrenia. Deficits of N-acetylaspartate (NAA) have been found in schizophrenia and bipolar disorder which may reflect neuronal loss and/or dysfunction. N-acetylaspartylglutamate (NAAG) is the most abundant peptide transmitter in the mammalian nervous system. It is an agonist at presynaptic metabotropic glutamate receptors mGluR3, inhibiting glutamate release. NAA and NAAG and were measured in hippocampal, striatal, amygdala and cingulate gyrus regions of human postmortem tissue from controls and subjects with schizophrenia, bipolar disorder and major depressive disorder. There are significant deficits in hippocampal NAA concentrations in all patient groups. In the amygdala there are significant NAA deficits in schizophrenia and depression and significant deficits of NAAG in the amygdala in the depression group. The deficits in NAA reported in this study confirm the importance of hippocampal and other subcortical structures in the neuropathology of the major psychiatric disorders.

Effect of social isolation on CB1 and D2 receptor and fatty acid amide hydrolase expression in rats

Rearing rats in isolation has been shown to produce behavioral and neurochemical alterations similar to those observed in psychoses such as schizophrenia. Also, a dysregulation in both the endocannabinoid and dopaminergic systems has been implicated in schizophrenia. The aim of this study was to determine if there are differences in CB1 receptor and fatty acid amide hydrolase (FAAH) protein expression, as well as D2 dopamine receptor expression in different brain regions in rats reared in different environmental conditions. Twenty-one-day-old male Sprague-Dawley rats were either reared in individual cages (isolated rats) or in group cages of six per cage (group-housed rats) for 8 weeks. Quantitative fluorescence immunohistochemistry was performed on brain slices using antibodies specific to the CB1 or D2 receptor, or the enzyme FAAH. Raising rats in isolation led to a significant decrease in CB1 receptor expression in the caudate putamen and the amygdala, a significant increase in FAAH expression in the caudate putamen and the nucleus accumbens core and shell, and no significant change in D2 receptor expression in any region studied. These results indicate that the endocannabinoid system is altered in an animal model of aspects of psychosis. This implies that rearing rats under different housing conditions may provide new insight into the role of the endocannabinoid system in the development of psychoses.

Behavioural and neurochemical effects of post-weaning social isolation in rodents-relevance to developmental neuropsychiatric disorders

Exposing mammals to early-life adverse events, including maternal separation or social isolation, profoundly affects brain development and adult behaviour and may contribute to the occurrence of psychiatric disorders, such as depression and schizophrenia in genetically predisposed humans. The molecular mechanisms underlying these environmentally induced developmental adaptations are unclear and best evaluated in animal paradigms with translational salience. Rearing rat pups from weaning in isolation, to prevent social contact with conspecifics, produces reproducible, long-term changes including; neophobia, impaired sensorimotor gating, aggression, cognitive rigidity, reduced prefrontal cortical volume and decreased cortical and hippocampal synaptic plasticity. These alterations are associated with hyperfunction of mesolimbic dopaminergic systems, enhanced presynaptic dopamine (DA) and serotonergic (5-HT) function in the nucleus accumbens (NAcc), hypofunction of mesocortical DA and attenuated 5-HT function in the prefrontal cortex and hippocampus. These behavioural, morphological and neurochemical abnormalities, as reviewed herein, strongly resemble core features of schizophrenia. Therefore unravelling the mechanisms that trigger these sequelae will improve our knowledge of the aetiology of neurodevelopmental psychiatric disorders, enable identification of longitudinal biomarkers of dysfunction and permit predictive screening for novel compounds with potential antipsychotic efficacy.

Fluorescence determination of N-acetylaspartic acid in the rat cerebrum homogenate using high-performance liquid chromatography with pre-column fluorescence derivatization

N-acetyl-L-aspartic acid (NAA) is an endogenous compound, and its brain concentration is suggested to be altered in neurological disorders. In the present study, a fluorescence determination method for NAA was developed by employing reversed-phase high-performance liquid chromatography (HPLC) with pre-column fluorescence derivatization using 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Using methylsuccinic acid as the internal standard, a linear calibration curve for NAA was constructed in the range 125-1000 microM (n=3). The detection limit on the column was approximately 5.0 fmol (signal-to-noise ratio 3). The proposed HPLC method was applied to determine NAA in the rat cerebrum homogenate. Cerebrum NAA was successfully determined using 10 microL of the homogenate, and the validation data for the proposed HPLC method demonstrated satisfactory results. Intra- and inter-day precision and accuracy were within 1.1-7.0 and -8.1-6.3%, respectively. The concentration of NAA in the male rat cerebrum (13 weeks old) was 84 +/-4.6 nmol/mg protein (n = 3) [corrected].

The neuronal pathology of schizophrenia: molecules and mechanisms

There is an accumulation of evidence for abnormalities in schizophrenia of both the major neurotransmitter systems of the brain – those of GABA (γ-aminobutyric acid) and glutamate. Initial studies have found deficits in the putative neuronal marker, N-acetylaspartate, in a number of brain regions in schizophrenia. The animal models have provided some interesting correlates and discrepancies with these findings. The deficit in inhibitory interneurons within structures implicated in schizophrenic symptomatology may well have direct functional relevance, and can be induced by animal models of the disease such as subchronic phencyclidine administration or social isolation. Their association with these animal models suggests an environmental involvement. A loss of glutamatergic function in schizophrenia is supported by decreases in markers for the neuronal glutamate transporter in striatal structures that receive cortical glutamatergic projections. Deficits in the VGluT1 (vesicular glutamate transporter-1) in both striatal and hippocampal regions support this observation, and the association of VGluT1 density with a genetic risk factor for schizophrenia points to genetic influences on these glutamatergic deficits. Further studies differentiating neuronal loss from diminished activity and improved models allowing us to determine the temporal and causal relationships between GABAergic and glutamatergic deficits will lead to a better understanding of the processes underlying the neuronal pathology of schizophrenia.

Chronic administration of clozapine alleviates reversal-learning impairment in isolation-reared rats

Isolation rearing has been used for inducing schizophrenia-like symptoms in rats. Human schizophrenics have deficits in prefrontal-dysfunction-related cognitive/behavioral flexibility. Rats with lesions of the medial prefrontal cortex perform poorly in reversal learning. It is uncertain whether isolation rearing, however, causes reversal-learning impairment in adult rats. Using the rotating T maze, this study examined the effect of chronic administration of clozapine on visual discrimination learning and reversal learning in isolation-reared and socially reared adult rats. The results show that isolation-reared rats without clozapine injection performed significantly worse than socially reared rats in reversal learning but not in acquisition learning. Chronic injection of clozapine (5 or 10 mg/kg) in isolation-reared rats significantly improved reversal learning but had no effects on acquisition learning. Further data analyses show that in both the inhibition phase and the new-strategy-acquisition phase of reversal learning, isolation-reared rats needed significantly more correct-response trials to reach the criterion than socially reared rats, and clozapine significantly reduced the isolation-induced impairment of reversal learning only in the new-strategy-acquisition phase. In socially reared rats, clozapine had a dose-related interfering effect on reversal learning but not acquisition learning. This study supports the use of isolation rearing as a model for investigating the neurodevelopmental hypothesis of schizophrenia.

Advances in the treatment of anxiety: targeting glutamate

Our current psychopharmacological treatments for anxiety disorders evince a number of shortcomings, including troublesome side effects and lack of primary effects. Whereas many new drugs have been developed in the past few decades, most are based on outmoded theories of the pathogenesis of these disorders (i.e., monoamine hypotheses), thus frustrating our ability to create more specific and effective interventions. Recently, however, the neurobiological literature has shown a convergence of findings focusing on the glutamatergic system in anxiety disorders, and the growth of pharmacological tools targeting these receptors has led to the development of novel treatments having anxiolytic effects in humans and animals alike. Additionally, as this system is showing promise as a final common pathway in the pathogenesis of anxiety disorders, we may be able to employ glutamate-specific neuroimaging techniques (e.g., N-acetyl-aspartate, GLX) to both guide treatment decisions and present reliable objective biomarkers for treatment efficacy.

The effect of Delta9-tetrahydrocannabinol on sensorimotor gating in socially isolated rats

Rearing rats in isolation produces behavioural and neurochemical alterations similar to those observed in schizophrenia. Cannabinoids have also been implicated in inducing psychotic symptoms. In this study, we investigate the effect of the major psychoactive constituent of cannabis and partial cannabinoid CB(1) receptor agonist Delta(9)-tetrahydrocannabinol (THC) on prepulse inhibition (%PPI) of the acoustic startle reflex and on habituation in socially isolated and grouped rats. Deficits in %PPI are reminiscent of sensorimotor gating deficits observed in psychoses. Male Sprague-Dawley rat pups (21 days old) were housed in either single cages (isolated) or in group cages of six per cage (grouped). Eight weeks later the effect of vehicle, THC and the CB(1) receptor antagonist SR 141716 on %PPI was tested. Vehicle treated isolated rats exhibited significantly reduced PPI compared with grouped rats. Isolated rats treated with THC had significantly lower %PPI than vehicle treated groups. This further decrease of %PPI by THC was reversed by pre-treatment with SR 141716, indicating that this effect was mediated by CB(1) receptors. THC had no significant effect on %PPI in grouped rats. SR 141716 had no significant effect on %PPI in either grouped or isolated rats. Habituation did not significantly alter in any treatment group in any treatment group. These results suggest that THC produces significant decreases in sensorimotor gating in rats with already dysfunctional sensorimotor gating processes, but not in normal rats. The lack of effect of SR 141716 in either grouped or isolated rats suggests that normal endocannabinoid function is not critical in sensorimotor gating processes.

Increased N-acetylaspartate in rat striatum following long-term administration of haloperidol

N-acetylaspartate (NAA) is present in high concentrations in the CNS and is found primarily in neurons. NAA is considered to be a marker of neuronal viability. Numerous magnetic resonance spectroscopy (MRS) and postmortem studies have shown reductions of NAA in different brain regions in schizophrenia. Most of these studies involved patients chronically treated with antipsychotic drugs. However, the effect of chronic antipsychotic treatment on NAA remains unclear. In the present study, we measured NAA in brain tissue taken from 43 male Long-Evans rats receiving 28.5 mg/kg haloperidol decanoate i.m. every 3 weeks for 24 weeks and from 21 controls administered with vehicle. Determination of tissue concentrations of NAA was achieved by HPLC of sections of frozen tissue from several brain regions with relevance to schizophrenia. Chronic administration of haloperidol was associated with a significant increase (+23%) in NAA in the striatum (p<0.05) when compared to controls, with no significant changes in the other regions investigated (frontal and temporal cortex, thalamus, hippocampus, amygdala, and nucleus accumbens). NAA appears to be selectively increased in the striatum of rats chronically receiving haloperidol. This increase may reflect a hyperfunction of striatal neurons and relate to the reported increase in somal size of these cells and/or the increase in synaptic density seen in this region following antipsychotic administration. The lack of effect in other regions indicates that the well-documented NAA deficits seen in chronically treated schizophrenia patients is not an effect of antipsychotic medication and may in fact be related to the disease process.