Postmortem evidence of structural brain changes in schizophrenia. Differences in brain weight, temporal horn area, and parahippocampal gyrus compared with affective disorder

Olfactory memory in unmedicated schizophrenics

Previous studies have indicated that schizophrenic patients have olfactory deficits. The question as to whether olfactory deficits are due to chronic effects of medication has not been addressed. This is the first paper to report that never-medicated schizophrenic patients also have olfactory deficits. Twenty four normal subjects and twenty unmedicated schizophrenic patients were examined with two tests of olfactory function: the University of Pennsylvania Smell Identification Test (UPSIT) and a match-to-sample olfactory memory test. Results indicated that schizophrenics did poorly on both the UPSIT and the olfactory match-to-sample memory test relative to sex and age-matched controls. ANCOVA showed that the deficit in performance on the olfactory match-to-sample test was still present even when the variance due to the UPSIT was taken out of the analysis. Deficits in olfactory identification and olfactory memory are consistent with the concept that schizophrenics have dysfunctional limbic systems.

Hippocampus-amygdala volumes and psychopathology in chronic schizophrenia

Volumes of the mesiotemporal structures (hippocampus-amygdala complex) were measured in 19 men who were chronic multiepisode schizophrenics and 18 age-matched healthy controls using T1-weighted contiguous coronal magnetic resonance images of 3.1-mm width. Using the level of the mammillary bodies as an anatomical landmark, the whole hippocampus-amygdala complex was divided into an anterior section (mainly containing amygdaloid tissue) and a posterior section (mainly containing the hippocampal formation). Total mesiotemporal tissue volume was reduced significantly in the patient group compared to controls (-11%), with significant reductions in both left (-20%) and right (-15%) hippocampal sections. Reduced limbic tissue volume was associated with increased severity of psychopathology. Severity of positive psychotic symptoms (Brief Psychiatric Rating Scale [BPRS] psychosis factor) was correlated significantly with right and left total mesiotemporal volumes (Spearman rho's = -0.61 p < 0.01). Negative symptom scores (BPRS anergia factor, Scale for Assessment of Negative Symptoms [SANS] global items) were not significantly correlated with any mesiotemporal tissue volumes. The data corroborate and extend previous findings of temporolimbic structure volume reduction in schizophrenia, and suggest that the positive psychotic symptoms of schizophrenia are associated with anatomic anomalies in mesiotemporal structure.

Learning and memory in monozygotic twins discordant for schizophrenia

Learning and memory were assessed in 24 monozygotic (MZ) pairs of individuals discordant for schizophrenia or delusional disorder and seven normal pairs of MZ twins. On declarative memory tasks, the affected group displayed a pattern that might best be characterized as dysmnesic in that they performed significantly worse than the discordant unaffected group on story recall, paired associated learning, and visual recall of designs, but they learned over time, had relatively preserved recognition memory, and did not show profoundly accelerated rates of forgetting. Effortful, volitional retrieval from the lexicon, measured by verbal fluency, was also compromised in the affected group. On the other hand, procedural learning of the motor skill in a pursuit rotor task was relatively intact in the affected group. Comparisons of the normal group and unaffected group indicated that the latter group had very mild impairments in some aspects of episodic memory, namely, immediate and delayed recall of stories and delayed recall of designs. It is highly unlikely that the impairments observed in the affected group can be attributed to differences in genome, family environment, socioeconomic circumstance, or educational opportunity, as all of these were controlled by the twin paradigm. Rather, the impairments appear to be related to the intercession of disease. The neuropsychological profile is consistent with frontal lobe and medial temporal lobe dysfunction, as noted in this sample as well as other samples of schizophrenic singletons. Significant correlations between many measures of memory and global level of social and vocational functioning within the discordant group were also found. Thus difficulties in rapidly acquiring new information and propitiously retrieving old information may burden patients with schizophrenia in many of the transactions of everyday life.

Reduced [3H]flunitrazepam binding in cingulate cortex and hippocampus of postmortem schizophrenic brains: is selective loss of glutamatergic neurons associated with major psychoses?

Findings. Specific [3H]flunitrazepam binding to "neuronal"-type sites was significantly lower in anterior cingulate cortex, hippocampus, somatomotor cortex, cerebellar cortex, and globus pallidus in small postmortem samples of schizophrenic brains than in non-schizophrenic controls. Four of these five brain regions were reported by others to exhibit atrophy and/or neuronal loss in schizophrenia.

INTERPRETATION

Selective loss of hippocampal pyramidal neurons in postmortem schizophrenic brains has been reported (11). Pyramidal neurons are known to be glutamatergic (14,26) and to exhibit high densities of benzodiazepine binding sites (25,31). Glutamatergic neurons are known to be abundant in most layers of the cerebral cortex, and most of these are pyramidal neurons (26). All layers of the cerebral cortex display high densities of benzodiazepine binding sites (24,25,31). The number of larger pyramidal cells is little affected in most layers of the anterior cingulate cortex, but the number of small neurons is significantly lower, particularly in layer II (10). Pyramidal neurons range in size from very large to very small, and many very small pyramidal cells are often counted, together with small "stellate" neurons, as "granule" cells (28). Further, non-pyramidal glutamatergic neurons are reportedly also found in cerebral cortex (26). Thus, it seems possible that the large reduction in [3H]flunitrazepam binding we find in anterior cingulate cortex reflects the selective loss of glutamatergic neurons. The hypothesis that selective loss of glutamatergic neurons form various brain regions is associated with major psychoses can be easily tested by immunohistochemical studies of these regions using glutamate- and GABA-specific antibodies.

Lateral asymmetries in auditory acuity distinguish hallucinating from nonhallucinating schizophrenic patients

Bilateral absolute auditory thresholds for frequencies ranging from 250 to 8000 Hz were examined on two occasions in schizophrenic patients and normal control subjects. Patients were classified as hallucinators and nonhallucinators on the basis of symptom ratings on both occasions. Previous evidence of better right than left ear acuity in schizophrenia was replicated but was found to characterize nonhallucinating patients only. Hallucinators showed no lateral asymmetry and inferior right ear acuity as compared with that in nonhallucinators. The results were reliable on retest. Brief Psychiatric Rating Scale scores of positive and negative symptoms in some cases differentiated hallucinators from nonhallucinators. The relationship of verbal hallucinations and right ear-left temporal lobe functions is discussed, together with complexities in cerebral laterality-syndrome relationships.

A computerized magnetic resonance imaging study of corpus callosum morphology in schizophrenia

The hypothesis tested was that, in schizophrenia, corpus callosum size would be reduced, particularly in the region responsible for communication between both temporal lobes. This is supported by knowledge of: (a) anatomical homotopicity and functional specialization of fibres within the corpus callosum; (b) evidence linking structural and functional deficits of the corpus callosum and left temporal lobe with schizophrenia; and (c) that temporal lobe neuronal fibres pass through the middle region of the corpus callosum. Brain area and corpus callosum areas, widths and length were measured on mid-sagittal MRI scans using a computer outlining method. Scans from 30 schizophrenics and 44 normal subjects were compared. Mid-sagittal brain area, corpus callosum area, length and anterior widths were reduced in the schizophrenic group compared with controls. A significant area difference between schizophrenics and controls was seen in the mid-corpus callosum which communicates between the temporal lobes, including the superior temporal gyri. In schizophrenics, corpus callosum area reduction was not accounted for by brain area shrinkage alone. Differences between the two groups were accounted for by comparisons between males only. These findings support the hypothesis and the possibility that localized abnormalities of bilaterally connected brain regions might have secondary effects on their homotopically distributed fibres within the corpus callosum.

P300 topographic asymmetries are present in unmedicated schizophrenics

Our laboratory has repeatedly found a left < right auditory P300 temporal lobe topographic asymmetry in right-handed, medicated schizophrenics. To determine whether this asymmetry was attributable to the effects of antipsychotic medications, we collected auditory "odd-ball" P300 event-related potentials from 14 right-handed, unmedicated schizophrenics (withdrawn from medication for an average of 21 days) and 14 right-handed, normal controls. Analysis of normalized P300 amplitudes showed a statistically significant difference in the voltage distributions between groups (a group by temporal electrode site interaction) that was consistent with a left < right temporal voltage asymmetry in schizophrenics but not in the normal controls. We conclude that P300 topographic asymmetries are present in unmedicated schizophrenics. These data are compatible with the growing body of data suggesting left temporal lobe structural abnormalities in schizophrenia.

Abnormal serine-glycine metabolism in the brains of schizophrenics

The metabolism of serine and glycine as studied in the plasma is abnormal in schizophrenics and psychotics. There is a concomitant abnormality of the enzyme serine hydroxymethyl transferase (SHMT). To study the status of serine-glycine metabolism in brains of schizophrenics and controls, frozen autopsied brain tissues were obtained from medial and lateral temporal lobes. The results show that the apparent Km of SHMT and the concentrations of serine and glycine are significantly higher only in the medial temporal lobe areas of schizophrenics when compared to controls. These findings are discussed in the context of the role of glycine and serine as enhancers of glutamatergic excitotoxicity and consequent development of morphological abnormalities in the brains of schizophrenics.

Hippocampal modulation of acoustic startle and prepulse inhibition in the rat

Prepulse inhibition (PPI) is the normal reduction in a startle response that occurs when the startling stimulus is preceded by a weak lead stimulus ("prepulse"). Schizophrenic patients exhibit abnormally low levels of PPI; therefore, animal models of deficient PPI may provide information regarding neural dysfunctions underlying schizophrenia. We recently reported that infusion of the cholinergic agonist carbachol into the dentate gyrus (DG) disrupts PPI in the rat. We now report the effects of carbachol microinjected into CA1, the DG, or the ventral subiculum (VS) on acoustic startle and PPI. Carbachol infusion into CA1 or the DG depressed startle. Carbachol infusion decreased PPI with a regional rank-order potency CA1 > DG > VS. CA1 infusions more potently depressed the startle reflex. By contrast, DG infusions preferentially decreased PPI, while VS infusions decreased PPI without altering startle amplitude. Coinfusion with the muscarinic cholinergic antagonist atropine opposed the effects of carbachol. These results demonstrate the regional heterogeneity and pharmacological specificity of the hippocampal cholinergic modulation of acoustic startle and PPI and suggest that abnormalities within various regions of the hippocampal formation may contribute to deficient sensorimotor gating in schizophrenic patients.

Study of chronic schizophrenics using 31P magnetic resonance chemical shift imaging

Phosphorus-31 chemical shift imaging showed regional abnormalities of in vivo 31P NMR spectra in the brains of chronic schizophrenic patients. In the left temporal region, the level of % phosphodiesters (PDE) was increased and the level of % gamma alpha beta-ATP (obtained by summation of gamma-ATP, alpha-ATP, and beta-ATP) was decreased. In the basal ganglia, the levels of % PDE were decreased and the level of % phosphomonoesters was increased. The levels of % gamma alpha beta-ATP were increased in the right basal ganglia. The level of % phosphocreatine was decreased in the frontoparietal region. These findings may represent different patterns of dysfunction of membrane phospholipid bilayers and high-energy phosphate metabolism in the specific cerebral regions.

Formal thought disorder in pediatric complex partial seizure disorder

We compared the formal thought disorder ratings of 27 children with complex partial seizure disorder, 31 schizophrenic children and 58 normal children. The epileptic children with fullscale IQ scores below 100 had significantly more formal thought disorder than normal children with a similar IQ. The severity of their formal thought disorder was related to the age of seizure onset, seizure control and a diagnosis of schizophrenia spectrum disorder. The schizophrenic children had thought disorder irrespective of IQ scores. The cognitive correlates of their formal thought disorder scores differed from those of the epileptic children. Possible anatomical substrates of thought disorder in childhood complex partial seizure disorder and schizophrenia are discussed.

From an animal model of an attentional deficit towards new insights into the pathophysiology of schizophrenia

The paper presents an animal model of schizophrenic-like attentional deficit, consisting of an inability to ignore irrelevant stimuli. It is based on the paradigm of latent inhibition (LI), in which animals learn to ignore repeatedly presented stimuli not followed by meaningful consequences. In a series of experiments it was demonstrated that the capacity to ignore irrelevant stimuli is lost in rats treated with systemic or intra-accumbens injections of amphetamine, in normal volunteers given amphetamine, in high "psychosis-prone" persons, in acute schizophrenic patients and in untreated male adult rats that were raised until weaning under conditions of extremely restricted stimulation. In addition, LI is lost following the disruption of the hippocampal input to the nucleus accumbens. In all of the above conditions tested for antagonism by anti-psychotic drugs a loss of LI is reversed. On the basis of these results we propose an animal model which accommodates a neurodevelopmental dysfunction, hippocampal pathology, mesolimbic DA overactivity, vulnerability to stress, and gender differences, all of which have been postulated as factors in the pathophysiology of schizophrenia.

Genes, viruses and neurodevelopmental schizophrenia

Recent neuroimaging and neuropathological studies suggest a developmental origin for schizophrenia. Some cases may, therefore, be caused by a genetic defect in the specification of brain development. Early environmental hazards such as obstetric complications, and maternal exposure during pregnancy to influenza epidemics, have also been found to increase the risk of later schizophrenia. The relationship between the prevalence of influenza and birth date has been found more consistently for female than male schizophrenics. Female schizophrenia is also associated with a higher risk of schizophrenia in first degree relatives. This raises the question of whether part of the genetic predisposition to schizophrenia may comprise an abnormal reaction to maternal influenza.

Abnormal premovement brain potentials in schizophrenia

We assessed scalp-recorded movement related potentials (MRPs) generated prior to voluntary movements in chronic, medicated schizophrenics (n = 9) and age matched normal controls (n = 9). MRPs were recorded in a self-paced button press task in which subjects pressed a button with either their right, left or both thumbs (experimental condition I, II and III respectively). Controls generated a slowly rising readiness potential (RP) at about 1000 ms, a negative shift (NS') at about 450 ms and a motor potential (MP) at about 100 ms prior to movement. The initial MRP components (RP and NS') were reduced in schizophrenics indicating an impairment of the voluntary preparatory process in schizophrenia. Results of the present study indicate a similarity of MRP findings in schizophrenics and reported MRPs (Singh and Knight, 1990) in patients with unilateral lesions of the dorsolateral prefrontal cortex. These findings provide further support for frontal lobe dysfunction in schizophrenia.

Behavioral markers of schizophrenia useful for genetic studies

The advent of powerful molecular biological techniques have already led to the discovery of chromosomal loci linked to some genetically transmitted diseases. These techniques, however, lose their power if applied to a disease trait that is not Mendelian in its transmission. The low familial prevalence of psychiatric diseases such as schizophrenia make these techniques unsuitable for linkage studies of these conditions, if identification of schizophrenia relies solely on the clinical manifestation of the schizophrenic psychosis. Broadening the disease phenotype in diseases such as schizophrenia, with low recurrence risk, and narrowing it in diseases such as major affective disorder, with very high recurrence risk, may be an effective strategy for linkage studies of these diseases. Several alternative phenotypes are discussed, including smooth pursuit eye movement abnormalities, event related potentials, and deficient attentional deployment as measured by the continuous performance test. The strategy assumes that schizophrenia is a pleiotropic disorder, and that the psychosis is the rare form of the condition. The paper focuses principally on smooth pursuit eye movement abnormalities, and claims a plausible place for them as an independent expression of schizophrenia. With this strategy, the possibility for successful linkage studies increases, since familial distributions of schizophrenia and pursuit abnormalities, considered together, appear to fit an autosomal dominant pattern.

The subcortical dysfunction hypothesis of memory deficits in depression: neuropsychological validation in a subgroup of patients

The subcortical dysfunction hypothesis of verbal learning and memory deficits in depression was evaluated by comparing the memory test profiles of unipolar depressives (n = 40) and bipolar depressives (n = 9) with those of patients with a prototypical subcortical dementia (Huntington's disease, HD), patients with a prototypical cortical dementia (Alzheimer's disease, AD), and normal controls. In a discriminant function analysis that well-differentiated the HD, AD, and normal subjects, it was found that 28.6% of the depressed patients were classified as HD patients (DEP-HD subjects), 49.0% were classified as normals (DEP-N subjects), none were classified as AD patients, and 22.4% were not well-classified. The DEP-HD group closely resembled the HD group on additional indices of verbal learning and memory, and differed from the DEP-N group, which strongly resembled the normal control group. DEP-N patients also performed significantly better than DEP-HD patients on a number of other neuropsychological tests (e.g., WAIS-R Digit Symbol, category fluency, Trail Making Test Part B). The findings provide support for the subcortical dysfunction hypothesis, but only for a subgroup of depressed patients. Implications for differentiating depressive "pseudodementia" from AD are discussed.

The meaning of basic symptoms for the genesis of the schizophrenic nuclear syndrome

In the Bonn Transition Sequences study, the development of the Schneiderian first rank symptoms in their exact chronological order was studied from the first symptomatological precursors up to the complete forms of the respective psychotic final phenomena. At their onset, subjective experiences of preexisting disorders of perception, thinking, speech and memory, of cognitive control of action and of proprioception were found. These four groups of initial deficiencies developed via certain intermediate phenomena into first rank symptoms. The analysis of these transition sequences revealed three phases with different generating factors each. Altogether, the results showed that and how the gap between the deficiency findings of the biologically oriented research in schizophrenia and the diagnostically relevant changes in experience can be bridged.

Abnormalities of the left temporal lobe and thought disorder in schizophrenia. A quantitative magnetic resonance imaging study

BACKGROUND

Data from postmortem, CT, and magnetic resonance imaging (MRI) studies indicate that patients with schizophrenia may have anatomical abnormalities of the left temporal lobe, but it is unclear whether these abnormalities are related to the thought disorder characteristic of schizophrenia.

METHODS

We used new MRI neuroimaging techniques to derive (without knowledge of the diagnosis) volume measurements and three-dimensional reconstructions of temporal-lobe structures in vivo in 15 right-handed men with chronic schizophrenia and 15 matched controls.

RESULTS

As compared with the controls, the patients had significant reductions in the volume of gray matter in the left anterior hippocampus-amygdala (by 19 percent [95 percent confidence interval, 3 to 36 percent]), the left parahippocampal gyrus (by 13 percent [95 percent confidence interval, 3 to 23 percent], vs. 8 percent on the right), and the left superior temporal gyrus (by 15 percent [95 percent confidence interval, 5 to 25 percent]). The volume of the left posterior superior temporal gyrus correlated with the score on the thought-disorder index in the 13 patients evaluated (r = -0.81, P = 0.001). None of these regional volume decreases was accompanied by a decrease in the volume of the overall brain or temporal lobe. The volume of gray matter in a control region (the superior frontal gyrus) was essentially the same in the patients and controls.

CONCLUSIONS

Schizophrenia involves localized reductions in the gray matter of the left temporal lobe. The degree of thought disorder is related to the size of the reduction in volume of the left posterior superior temporal gyrus.

Cerebrospinal fluid and serum levels of neuron-specific enolase in patients with schizophrenia

Some patients with schizophrenia appear to have brain abnormalities, including enlarged third and lateral ventricles and reduced volumes of temporal lobe structures. These abnormalities could be attributed to a developmental abnormality or a neurodegenerative process. Neuron-specific enolase (NSE), a protein that is found primarily in neurons and neuroendocrine cells, has been used as an index of neuronal damage or degeneration. Levels of NSE in cerebrospinal fluid (CSF) and serum from 50 patients with acute and chronic schizophrenia were compared with those in normal and neurological control subjects. A double-antibody, solid phase iodinated radioimmunoassay was used to determine NSE levels. There was no evidence of elevated levels in patients with schizophrenia, whereas control subjects with neurological illnesses had increased levels of NSE in CSF. Because NSE is rapidly cleared from CSF, however, elevated levels could have been missed. Unmedicated patients tended to have lower levels than medicated patients.

31Phosphorus magnetic resonance spectroscopy of the temporal lobes in schizophrenia

Eleven schizophrenic patients and nine normal controls were studied using in vivo 31Phosphorous magnetic resonance spectroscopy (31P MRS) to test the hypothesis of metabolic asymmetry in the temporal lobes in schizophrenia. The controls did not demonstrate any asymmetry of phosphorous metabolite ratios, percentage of phosphorous metabolites, or pH. In the schizophrenics, however, phosphocreatine/beta-adenosine triphosphate (PCr/beta-ATP) and phosphocreatine/inorganic phosphate (PCr/Pi) effects appeared to primarily reflect higher ratios on the right side, while the percentage of beta-ATP appeared to primarily reflect higher relative concentrations in the left temporal lobe. Moreover, significant negative correlations were noted between total Brief Psychiatric Rating Scale scores and PCr/beta-ATP in both the right and left temporal lobes. These results support the hypothesis of an asymmetric distribution of 31P metabolites in the temporal lobe of schizophrenic patients, and also show an association between temporal lobe phosphorous metabolism and the severity of psychiatric symptomatology.

Regionally selective deficits in uptake sites for glutamate and gamma-aminobutyric acid in the basal ganglia in schizophrenia

In a post-mortem study of schizophrenic and control subjects, the sodium-dependent binding of D-[3H]aspartate and [3H]nipecotic acid were used to investigate uptake sites of glutamate and gamma-aminobutyric acid (GABA), respectively, in subcortical brain regions. Binding to the glutamate uptake site was substantially reduced in both the putamen and lateral pallidum of the schizophrenic subjects. Binding to the GABA uptake site was substantially reduced in the putamen; smaller reductions were apparent in the caudate nucleus and lateral pallidum. The results suggest that glutamatergic and GABAergic mechanisms in the basal ganglia are abnormal in schizophrenia. These abnormalities could be relevant to the development of psychosis but could also relate to the spectrum of mild motor disturbances often described in the disease.

The role of right hemisphere dysfunction in psychiatric disorders

In 1861 Broca, a Parisian surgeon, reported a postmortem he had carried out on a man who had lost his ability to speak 20 years previously and who in the intervening period had only regained the use of one phrase: “Tan-tan”. Broca found that this man had an old infarct in his left hemisphere, affecting the posterior portions of the second and third frontal gyri.

Sensory gating in rats depleted of dopamine as neonates: potential relevance to findings in schizophrenic patients

Based on a recent hypothesis of reduced subcortical dopaminergic tone, evidence of early neurodevelopmental deviation, and acoustic startle abnormalities in schizophrenia, we examined acoustic startle in adult animals depleted of dopamine (DA) as neonates. Male rat pups received intracerebroventricular injections of either 6-hydroxydopamine (6-OHDA, 100 micrograms) or its vehicle on postnatal day 3. At 60 days of age, baseline startle and prepulse inhibition (PPI) of startle were assessed in a no injection condition, with all other animals receiving injections of saline or the DA agonist, apomorphine. Acoustic startle was elicited using 120 db white noise bursts alone or preceded by prepulses of 75, 80, and 85 db. Animals treated with 6-OHDA exhibited a 93% depletion of striatal DA compared to vehicle-treated controls. Whereas DA depleted animals did not differ from controls in the no injection condition, they showed greater baseline startle and reduced PPI compared to controls after saline injections. Depleted animals also showed exaggerated responses to apomorphine, with greater increases in baseline startle, loss of habituation, and decreased PPI compared to controls. Findings indicate that neonatal DA depletions lead to increased baseline startle and impaired sensory gating in adulthood after saline injections and dopamine agonists compared to controls. These findings may be relevant to a subgroup of psychotic patients that exhibit similar startle abnormalities as well as signs of hypodopaminergic function.

Is the concept of frontal-subcortical dementia relevant to schizophrenia?

A syndrome of subcortical dementia has been described in conditions predominantly affecting the basal ganglia or thalamus, structures that have also been implicated in the pathogenesis of schizophrenia. There are similarities between subcortical dementia and the type II syndrome of schizophrenia, in terms of clinical features, pattern of neuropsychological deficits, pathology, biochemistry and data from brain-imaging studies. These similarities raise the possibility that certain schizophrenic symptoms, particularly negative symptoms and disturbance of movement, may reflect subcortical pathology. Neuropsychological deficits of presumed frontal lobe origin have been reported in some schizophrenic subjects. The occurrence of such deficits in a condition in which frontal lobe pathology has not been clearly demonstrated may be explicable in terms of a subcortical deafferentation of the pre-frontal cortex.

A developmental perspective on the pathology and neurochemistry of the temporal lobe in schizophrenia

Neuropathological, neuroimaging, clinical and epidemiological evidence suggests that many cases of schizophrenia are developmental in origin. Dysplastic changes in the medial temporal lobes appear to be of particular importance. However, research implicating a neurodevelopmental origin for schizophrenia has proceeded largely in isolation from knowledge concerning the neurochemistry of the disorder. This paper attempts to integrate these disparate lines of research, and examines the role of trophic mechanisms in the formation of the hippocampus. Those neurotransmitters which have been most consistently found to be abnormal in the temporal lobes of schizophrenics (excitatory amino acids and CCK), are involved in the control of hippocampal development. We suggest that these neurotransmitter findings are the residue of abnormalities in their role as trophic factors in foetal or neonatal life, and that the latter contribute to the developmental aberrations considered fundamental to schizophrenia.

Ventricular enlargement, clinical correlates and treatment outcome in chronic schizophrenic inpatients

The ventricle-brain ratio (VBR) of 42 chronic schizophrenic patients was compared with that of 42 age-matched medical controls. For the schizophrenics, the relationship of various clinical parameters to the VBR was assessed, and the outcome of 12 weeks of double-blind treatment with either risperidone or haloperidol. The results confirm that schizophrenic patients have slightly enlarged lateral ventricles compared with medical controls. Only for schizophrenics, an effect of age, but not of duration of illness, was noticed. This study does not support the validity of a clinical subdivision of chronic schizophrenic patients on the basis of the VBR. Neither negative, positive nor general psychopathological symptoms, as measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS), were related to the VBR, nor were abnormal involuntary movements or extrapyramidal symptoms. No association between season of birth or a family history of major mental disorder and VBR could be demonstrated. Treatment response was predicted by the total PANSS score and the PANSS general psychopathology subscale score at baseline. There was a trend for patients with higher VBR to have a more or haloperidol). or haloperidol).

Loss of sylvian fissure asymmetry in schizophrenia. A quantitative post mortem study

The sylvian fissure is known to be one of the most asymmetric structures of the human brain. Sylvian fissure length was measured in post-mortem brains of 35 schizophrenic patients and 33 matched non psychiatric control subjects. The schizophrenics showed a significantly reduced length of the left sylvian fissure (-16%, p less than 0.0001) compared to the control subjects, while the right sylvian fissure length was unchanged. Sylvian fissure asymmetry (left/right ratio) was more reduced in male schizophrenics (-24%, p less than 0.001) than in female patients (-16%, p less than 0.03). This finding is consistent with several post-mortem and MRI studies showing left temporal lobe pathology in a significant proportion of patients and may indicate that schizophrenia is a disorder of early neurodevelopment causing impaired cerebral lateralization.

Paranoid schizophrenia may be caused by dopamine hyperactivity of CA1 hippocampus

Explicit consolidation of memory, or fixation of declarative belief, appears to be physically represented in changes of synaptic conductances of neurons in the parietal-temporal-occipital association cortex (PTO) of the mammalian forebrain. This fixation of belief in PTO is postulated to be critically dependent on a diffuse reinforcement signal via the inferior temporal cortex (ITC) ultimately caused by an increased output of the CA1 pyramidal cells of hippocampus. Analogous to the reinforcing mechanisms of other forebrain systems, this updating of the connection weights of the neural nets in PTO by the output of the critical neurons in CA1 is directly related to concentrations of dopamine (DA). We propose that the delusions (i.e., unreasonable beliefs) of paranoid schizophrenia are caused by a hyperactivity of the same DA-sensitive CA1 neurons that are responsible for the fixation of normal beliefs. The dramatic reduction in delusions with administration of neuroleptics, as DA D2 blockers, in schizophrenics may thus be explained by their acting to ameliorate the hyperactivity of these CA1 DA D2 receptors.

Distribution of beta-adrenergic receptor subtypes in human post-mortem brain: alterations in limbic regions of schizophrenics

The distribution of the beta 1 (beta 1) and beta 2 (beta 2) subtypes of the beta-adrenergic receptor was examined in rat and nondiseased control human tissue. The distribution of the beta 1 and beta 2 receptors was also examined in schizophrenic cases, with additional studies in schizophrenic suicide and nonschizophrenic suicide cases. Scatchard analysis of the binding of [125I]iodopindolol (IPIN) to cortical membranes showed a similar Kd in human (177 pM) and rat (161 pM), but a lower maximum binding site (Bmax) in the human tissue (18.7 fmol/mg protein and 55.6 fmol/mg protein). For the autoradiographic studies [125I]IPIN was used to visualize both subtypes (total) or was displaced with the selective beta 1-receptor antagonist ICI-89,406 to visualize beta 2 sites, or with the selective beta 2-receptor antagonist ICI-118,551 to visualize beta 1 sites. Important differences in the regional distribution of the two subtypes of the beta-adrenergic receptors were noted between rat and human. In the nucleus accumbens and ventral putamen (ventral striatum), a patchy distribution of beta 1 receptors was observed that was not evident in the rat. These patches were aligned with markers of the matrix compartment of the striatum. The schizophrenic cases showed significant increases in the labeling of the beta 1-receptor patches with [125I]IPIN. In contrast to the frontal cortex of the nondisease controls, the parietal and temporal cortex showed a high ratio of beta 1 to beta 2 receptors and a highly laminar organization of the subtypes. [125I]IPIN binding to beta 1 receptors was highest in the external laminae with the reverse gradient for the beta 2 subtype. The medial temporal cortex displayed an alteration in the ratio of the 2 subtypes of the beta-adrenergic receptor, with the parahippocampus and hippocampus of the human, in contrast to the rat brain, predominantly expressing the beta 2 receptor. Moreover, there were consistently higher densities of beta 2 receptors in the hippocampus of the right hemisphere than the left hemisphere of the nondisease controls. There was not a left and right hemispheric asymmetry of beta 2 receptors in the hippocampus of elderly schizophrenics or in young schizophrenics who committed suicide. The asymmetry was evident in nonschizophrenic suicides, suggesting that the lack of asymmetry in the hippocampus of schizophrenics is evident early in the disease process. Thus limbic structures show alterations in the patterning of beta 1 and beta 2 receptors in the schizophrenic cases.

Distribution of CCK binding sites in the human hippocampal formation and their alteration in schizophrenia: a post-mortem autoradiographic study

The distribution of cholecystokinin binding sites has been visualized and quantified by quantitative autoradiography in the human hippocampus from post-mortem brains of 11 controls and 11 schizophrenics. CCK receptors were localized to subiculum and parahippocampal gyrus. In the cortical areas there was a particularly dense lamination of receptors. In the schizophrenic material a similar overall pattern was seen, but there were significant losses of receptors in CA1 subiculum and cortex. These findings confirm the distribution of CCK receptors in the retrohippocampal areas in man and also provide further support for earlier homogenate studies which have also shown a loss of CCK binding sites in schizophrenia. This effect was localized primarily to parahippocampal gyrus suggesting that CCK plays some role in the genesis of developmental abnormalities in this region.

Subcortical and temporal structures in affective disorder and schizophrenia: a magnetic resonance imaging study

Volumetric measurements of subcortical and temporal structures were done on a sample of 54 schizophrenic patients, who were compared with 48 bipolar patients and 47 normal controls. We observed the male schizophrenic patients to have significant enlargement in the putamen and lesser enlargement in the caudate. We found the right temporal lobe to be larger than the left across all diagnostic groups, although bipolar females failed to have this asymmetry. We did not replicate the finding of decreased hippocampal, amygdala, or temporal lobe volume in our schizophrenic patients. Nor did we find significant differences between our bipolar patients and controls in the structures measured, with the exception of the right hippocampus. Our findings are consistent with a developmental defect in pruning of subcortical brain regions or with a compensatory synaptic increase secondary to decreased input from other brain regions such as the prefrontal cortex or anterior temporal lobe structures. Coupled with the lack of temporal lobe asymmetry in bipolar females, these findings suggest that different types of gender-specific neurodevelopmental abnormalities may occur in affective versus schizophrenic psychosis, which may reflect the effects of hormonal influences on brain development in predisposed individuals.

MRI and cognitive behavioral function in schizophrenia

There is active research applying MRI to the study of brain anatomy in schizophrenia. As the technology improves and measurements are refined, this method, in combination with behavioral measures, is likely to contribute to the understanding of brain function in schizophrenia. The heterogeneity of schizophrenia challenges investigators to integrate anatomic and behavioral parameters with physiology. MRI techniques have already been applied to obtain quantitative imaging of cerebral blood flow and holds promise for combined MRI and neurobehavioral studies.

Merck, Sharp & Dohme Prize for Young Psychopharmacologists: A history of frontal and temporal lobe aspects of the neuropharmacology of schizophrenia

In the past two decades neurobiological research into schizophrenia has seen a shift of emphasis from the dopaminergic pharmacology of subcortical systems to areas of abnormality inferred from direct studies, i.e. frontal cortex and medial temporal lobe. Recent research has tried to integrate morphological abnormalities with neurochemical and pharmacological data. These integrated approaches have uncovered neurochemical systems other than dopamine which are of importance. This approach has led to greater understanding of neurochemical mechanisms associated with these abnormalities and may provide novel approaches for therapeutic intervention.

Deficient NMDA-mediated glutamate release from synaptosomes of schizophrenics

Previous studies from our laboratory indicated that the veratridine-induced release of glutamate and GABA from synaptosomes derived from brains of schizophrenics was decreased. In the present study, synaptosomes were prepared from frozen brain samples from schizophrenics and from controls. Stimulation by 10 mumol/L 2-amino-3-hydroxy-5-methoxylisoxazole-4-propionic acid (AMPA) produced equal glutamate release from both groups. Release induced by either 10 mumol/L kainic acid (KA) or n-methyl-d-asparate (NMDA) was reduced significantly in the preparations derived from schizophrenics. Similarly, the amount of GABA released by 50 mumol/L glutamate was also reduced in the schizophrenic-derived synaptosomes. However, in membranes derived from the crude synaptosomal pellet, no differences between the controls and schizophrenics were observed in measures of total glutamate binding or its displacement by NMDA. The data demonstrate a deficiency in NMDA (and possibly KA) receptor functioning schizophrenics and support the "second-generation" theories of schizophrenia as a glutamatergic deficiency disorder.

Neuropsychological probes of fronto-limbic system dysfunction in schizophrenia. Olfactory identification and Wisconsin Card Sorting performance

Schizophrenic patients and normal control subjects took the University of Pennsylvania Smell Identification Test (UPSIT) and Wisconsin Card Sorting Test (WCST) as dual neuropsychological 'probes' of orbitofrontal (OF) and dorsolateral (DL) prefrontal function respectively. Patients were significantly impaired on both tasks compared to controls. UPSIT and WCST performance were uncorrelated in patients but were positively correlated in controls. The lack of correlation found in the patients suggests that the tasks may be tapping independent dysfunctions in schizophrenia reflecting differential impairment in fronto-limbic brain systems. Individual profiles of preserved and impaired performance on the UPSIT and WCST suggested that three schizophrenic patients had OF dysfunction, five had DL dysfunction and seven had a generalized (OF and DL) frontal system dysfunction. The reduced ability of schizophrenic patients to identify odors was largely independent of many deficits or confounds typically associated with schizophrenia and did not appear to be simply a function of generalized deficit. These data are preliminary and require replication with larger samples and validation with other measures of fronto-limbic system dysfunction.

Abnormal expression of two microtubule-associated proteins (MAP2 and MAP5) in specific subfields of the hippocampal formation in schizophrenia

A variety of cytoarchitectural disturbances have been described in limbic regions in postmortem studies of schizophrenia, many of which suggest a developmental disturbance of normal neuronal geometry. This geometry is established and maintained by elements of the neuronal cytoskeleton. Immunohistochemistry with a panel of 15 monoclonal antibodies was used to monitor the presence of neuronal cytoskeletal proteins in the hippocampal formations of six patients with schizophrenia, six normal controls, and six with neurodegenerative disorders. In five of the six subjects with schizophrenia, prominent and specific alterations were found in the distribution of two microtubule-associated proteins, MAP2 and MAP5, which were anatomically selective for the subiculum and entorhinal cortex. In contrast, the immunoreactivity of other cytoskeletal proteins (i.e., tau, tubulins, and selected neurofilament protein phosphoisoforms) was similar for all subjects. Defects in the expression of MAP2 and MAP5, two proteins that contribute to the establishment and maintenance of neuronal polarity, could underlie some of the cytoarchitectural abnormalities described in schizophrenia and impair signal transduction in the affected dendrites. The subiculum and entorhinal cortex interconnect the hippocampal formation with widespread cortices and subcortical nuclei and play important roles in higher cognitive functions. Hence, pathologic lesions that distort the polarized geometry of neurons could play a role in the emergence of aberrant behavior in schizophrenia.

Positron emission tomography and magnetic resonance imaging: a review and a local circuit neurons hypo(dys)function hypothesis of schizophrenia

A review of brain imaging (PET and MRI) studies on schizophrenia and recent data from neuroanatomy, neurophysiology, neuropathology, neurochemistry, neuropsychology, and cortical organization theory is integrated with the concept of local circuit neurons (LCNs) in a new hypothesis--the local circuit neurons hypo(dys)function hypothesis of schizophrenia--that attempts to explain the pathogenesis and pathophysiology of schizophrenia through a hypofunction (or dysfunction) of the local circuit neurons in prefrontal and limbic-temporal areas. This hypofunction (dysfunction) is then related to the neurocircuitry, neuropsychology, and psychopathology of schizophrenia.

Middle childhood onset of interictal psychosis

The authors describe three children (mean age = 7.8 years) with complex partial epilepsy, left temporal lobe involvement, and interictal schizophrenia-like psychosis. As described in adults with complex partial epilepsy, these children met DSM-III criteria for schizophrenia, their affect was intact, and they demonstrated no negative signs of schizophrenia. Unlike adult epileptic patients, these children demonstrated psychotic symptomatology despite inadequate seizure control and after a short latency period. The possible role of early onset seizures, temporal lobe lesions, and kindling on the developing brain are discussed.

Magnetic resonance imaging in schizophrenia: altered brain morphology associated with P300 abnormalities and eye tracking dysfunction

This study was designed to investigate whether auditory P300 event-related potential and smooth pursuit eye-movement abnormalities in schizophrenia are associated with brain structural changes measured using magnetic resonance imaging (MRI). Serial coronal MRI scans obtained from 31 schizophrenic subjects and 33 volunteer controls were analysed by a rater who had no knowledge of the subjects' diagnoses. The brain areas measured bilaterally were the temporal lobe, hippocampus, amygdala, parahippocampal gyrus, head of caudate, cingulate cortex, frontal cortex, and the lateral ventricles. The area of the third ventricle, the thickness of the corpus callosum, and the intracranial area were also measured. Auditory P300 and eye tracking performance were recorded on all subjects. There was a significant increase in the latency and a reduction in amplitude of the P300 in the schizophrenic group. Only in the schizophrenic group was P300 latency correlated negatively with the area of the right and left cingulate cortex and positively with the difference in size between the right and left amygdala. In the subgroup of schizophrenic subjects whose P300 latency was greater than 2 standard deviations above the control mean, the area of the left cingulate cortex was significantly smaller than in controls, and the absolute right-left difference in the area of the amygdala was significantly increased. Eye tracking dysfunction in schizophrenia was not related to changes in the amygdala or cingulate cortex but was significantly correlated with enlargement of the lateral ventricles. Schizophrenic subjects with poor eye tracking had significantly larger lateral ventricles than controls. Eye tracking dysfunction, but not P300 abnormality, was correlated with the severity of both positive and negative symptom of schizophrenia. These findings demonstrate that psychophysiological abnormalities are associated with altered brain structure in schizophrenia.

Application of automated MRI volumetric measurement techniques to the ventricular system in schizophrenics and normal controls

As an initial approach to computer-automated segmentation of cerebral spinal fluid (CSF) vs. brain parenchyma in MR scans, and the transformation of these data sets into volumetric information and 3D display, we examined the ventricular system in a sample of ten chronic schizophrenics with primarily positive symptoms and 12 normal subjects. While no significant differences were noted between groups on volumetric measures of ventricular brain ratio or lateral ventricle size, normals showed a pattern of left greater than right lateral ventricular volume asymmetry not present in the schizophrenics. Within the schizophrenic group, departure from the normal left greater than right pattern was highly correlated with thought disorder.

Head circumference in elderly long-stay patients with schizophrenia

The head circumference of a long-stay population with schizophrenia was compared with that of a population with dementia, matched for sex and year of birth. Schizophrenics had a smaller head circumference, even after correction for height and weight. This confirms earlier but inconclusive and controversial reports, and might be taken as supporting a neurodevelopmental hypothesis of the aetiology of schizophrenia.

Two modes of central gaze fixation maintenance and oculomotor distractibility in schizophrenics

Distractibility defined operationally as a lack of stability in central-gaze fixation has been studied using two different oculomotor tasks that require the suppression of reflexive saccades triggered by the sudden appearance of novel, peripheral visual stimuli. In the first task ('Instructed'), maintenance of central gaze fixation was based on verbal instruction, whereas, in the second task ('Non-Instructed'), it was based upon a foveating mechanism maintained by sensory stimulation during the performance of a categorization task. 15 schizophrenics and 20 healthy control subjects were tested in the two tasks. Schizophrenics made more saccades than control subjects in the Instructed task only. The Instructed task saccade rate correlated significantly with scores on neuropsychological tests sensitive to frontal lobe dysfunction. Because the type of deficit observed in schizophrenics resembled that previously seen in patients with unilateral lesions of the ventrolateral convexity of frontal lobe, frontal lobe dysfunction was proposed as underlying the high task-specific distractibility of schizophrenics.

Limbic/mesolimbic connections and the pathogenesis of schizophrenia

The development of models of the pathogenesis of neuropsychiatric diseases that build on recent advances in chemical neuroanatomy will help to guide future research. The interconnections among limbic, basal ganglia, and cortical structures are used to form the basis of a hypothesis of the pathogenesis of schizophrenia. The adaptive capacity of subcortical dopamine systems is advanced as an explanation of the many states of the disease.

Performance of long-stay schizophrenics on matched verbal and visuospatial recall tasks

A verbal and a visuospatial recall task were compared for discriminating power, using the matched-tasks methodology. These tasks were administered to long-hospitalized schizophrenics. No evidence of a differential deficit, that is, better recall of either the verbal or the visuospatial materials, emerged in the patients. The results replicate a former finding showing no difference between verbal and visuospatial recall in schizophrenics, using memory tasks which were less sensitive as left- and right-hemisphere measures and a non-verbal task less affected by verbal mediation. This replication questions the assumption that the hemispheric differences observed in schizophrenics affect such memory tasks.