Neuropathological substrate of incident dementia in older patients with schizophrenia: A clinicopathological study.

AIM: Clinical studies reported that patients with schizophrenia are at a higher risk of developing dementia than people without schizophrenia. However, early neuropathological studies have shown that the incidence of Alzheimer's disease (AD) in schizophrenia patients does not differ from that in controls. These inconsistent results may be attributable to the inclusion of non-AD dementia, but there have been few clinicopathological studies in older patients with schizophrenia based on the current neuropathological classification. This study aimed to investigate the neuropathological basis of incident dementia in older patients with schizophrenia. METHODS: We systematically examined 32 brains of old patients with schizophrenia using standardized pathological methods. The severity of dementia-related neuropathologies was analyzed using standardized semiquantitative assessments. After excluding patients who fulfilled the neuropathological criteria, clinicopathological variables were compared between patients with and without incident dementia to identify potential differences. RESULTS: Seven patients fulfilled the pathological criteria for AD (n = 3), argyrophilic grain disease (AGD) (n = 2), dementia with Lewy bodies (n = 1), and AGD/progressive supranuclear palsy (n = 1). Among 25 patients for whom a neuropathological diagnosis was not obtained, 10 had dementia, but the clinicopathological findings did not differ from the remaining 15 patients without dementia. CONCLUSION: Two types of older schizophrenia patient present dementia: patients with co-existing neurodegenerative disease and patients who do not meet pathological criteria based on the current classification. To understand the neurobiological aspects of incident dementia in older patients with schizophrenia, further clinicopathological studies are needed that do not simply analyze incident dementia as a comorbidity of conventional dementia-related neuropathologies.

Schizophrenia-Like Behavioral Impairments in Mice with Suppressed Expression of Piccolo in the Medial Prefrontal Cortex.

Piccolo, a presynaptic cytomatrix protein, plays a role in synaptic vesicle trafficking in the presynaptic active zone. Certain single-nucleotide polymorphisms of the Piccolo-encoding gene PCLO are reported to be associated with mental disorders. However, a few studies have evaluated the relationship between Piccolo dysfunction and psychotic symptoms. Therefore, we investigated the neurophysiological and behavioral phenotypes in mice with Piccolo suppression in the medial prefrontal cortex (mPFC). Downregulation of Piccolo in the mPFC reduced regional synaptic proteins, accompanied with electrophysiological impairments. The Piccolo-suppressed mice showed an enhanced locomotor activity, impaired auditory prepulse inhibition, and cognitive dysfunction. These abnormal behaviors were partially ameliorated by the antipsychotic drug risperidone. Piccolo-suppressed mice received mild social defeat stress showed additional behavioral despair. Furthermore, the responses of these mice to extracellular glutamate and dopamine levels induced by the optical activation of mPFC projection in the dorsal striatum (dSTR) were inhibited. Similarly, the Piccolo-suppressed mice showed decreased depolarization-evoked glutamate and -aminobutyric acid elevations and increased depolarization-evoked dopamine elevation in the dSTR. These suggest that Piccolo regulates neurotransmission at the synaptic terminal of the projection site. Reduced neuronal connectivity in the mPFC-dSTR pathway via suppression of Piccolo in the mPFC may induce behavioral impairments observed in schizophrenia.

Clinicopathological investigation of the background of cognitive decline in elderly schizophrenia.

OBJECTIVE: We have often observed dementia symptoms or severe neurocognitive decline in the long-term course of schizophrenia. While there are epidemiological reports that patients with schizophrenia are at an increased risk of developing dementia, there are also neuropathological reports that the prevalence of Alzheimer's disease (AD) in schizophrenia is similar to that in normal controls. It is difficult to distinguish, based solely on the clinical symptoms, whether the remarkable dementia symptoms and cognitive decline seen in elderly schizophrenia are due to the course of the disease itself or a concomitant neurocognitive disease. Neuropathological observation is needed for discrimination. METHODS: We conducted a neuropathological search on three cases of schizophrenia that developed cognitive decline or dementia symptoms after a long illness course of schizophrenia. The clinical symptoms of total disease course were confirmed retrospectively in the medical record. We have evaluated neuropathological diagnosis based on not only Hematoxylin-Eosin and Klüver-Barrera staining specimens but also immunohistochemical stained specimens including tau, ß-amyloid, pTDP-43 and α-synuclein protein throughout clinicopathological conference with multiple neuropathologists and psychiatrists. RESULTS: The three cases showed no significant pathological findings or preclinical degenerative findings, and poor findings consistent with symptoms of dementia were noted. CONCLUSION: Although the biological background of dementia symptoms in elderly schizophrenic patients is still unclear, regarding the brain capacity/cognitive reserve ability, preclinical neurodegeneration changes in combination with certain brain vulnerabilities due to schizophrenia itself are thought to induce dementia syndrome and severe cognitive decline.

Background of the neuropathological site in neurocognitive decline in elderly schizophrenic patients.

We herein report the neuropathological findings of a schizophrenic patient who showed cognitive decline and deterioration of psychiatric symptoms in his elderly years. In the neuropathological investigation in this case, Alzheimer-type pathology and argyrophilic grain pathology were observed. Schizophrenic patients can sometimes show cognitive decline in later life as an intrinsic symptom. However, they may also be complicated with dementia in later life, although these complications in a clinical setting have not been well examined. Few reports have investigated whether or not schizophrenic patients are likely to be complicated with dementia, and the findings remain controversial. We confirmed relatively mild ageing changes neuropathologically in the present case. How much these pathological changes influenced his psychiatric symptoms is unclear, but these changes were thought to have some degree of relevance. We also discuss the relationship between schizophrenia and dementia. We should remain alert to the fact that even schizophrenic patients can contract neurodegenerative diseases as a dual diagnosis in their clinical course and that they can show complicated symptoms. Further investigations of the clinical-pathological relationship between schizophrenia and dementia are thus needed.

Globular glial tauopathy Type I presenting with behavioral variant frontotemporal dementia.

Globular glial tauopathy (GGT) is a recently proposed tauopathy characterized by the globular accumulation of four-repeat (4R) tau in the oligodendroglia (globular oligodendroglial inclusion (GOI)) and astrocytes (globular astrocytic inclusion (GAI)), in addition to deposition in neurons. Although it is proposed that GGT should be classified into three different neuropathological subtypes, previous reports have indicated that subclassification might be difficult in some cases. We report an autopy case of a 79-year-old man with behavioral variant frontotemporal dementia (bvFTD). He developed behavioral changes at 67 years of age and had auditory hallucinations and persecutory delusions at admission to a psychiatric hospital at 69 years of age. Neuropathologically, marked atrophy of the frontotemporal lobes and severe degeneration of the white matter and frontopontine tract were observed. The present case corresponded to GGT Type I, as numerous GOIs were observed, predominantly in the frontotemporal region. However, concurrent degeneration of the motor cortex and corticospinal tract suggest characteristics of Type II. Although the relationship between psychotic symptoms and GGT remains unclear, the present case demonstrates heterogeneity of GGT subtypes.

Clinicopathological differences between the motor onset and psychiatric onset of Huntington's disease, focusing on the nucleus accumbens.

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder characterized by the presence of chorea, psychiatric symptoms, and dementia. Although motor symptoms are thought to be correlated with the degeneration of the striatum, there is little information regarding the neuropathological basis of psychiatric symptoms. The ventral part of the striatum is known as the nucleus accumbens (Acb) and is a region of interest as a responsible focus of psychiatric symptoms. The purpose of this study was to investigate the neuronal changes in the Acb and its relevance to psychiatric symptoms in HD. We investigated the brains of 16 HD patients (three patients presented psychiatric symptoms as the onset phenotype (HD-P), 13 patients presented motor symptoms as the onset phenotype (HD-M)) and four control subjects. The numerical cell densities for each of the large and small striatal neurons in the Acb, caudate nucleus and putamen were measured at three levels from the caudal to rostral region. As the result, the median small neuronal densities in all striatal regions in the HD brains were significantly lower than controls. Regarding the median small neuronal density in the caudate nucleus and putamen among the three levels, there were significant differences in the HD brains, but not in controls. The median large neuronal density in the Acb was significantly higher in the HD-P than in the HD-M, but there was no difference in the median small neuronal density between them. In the present study, we revealed that the Acb as well as the caudate nucleus were affected in HD brains. In terms of neuronal size and caudal to rostral levels, non-uniform neurodegeneration was observed in the striatum of the HD brains. The pathological difference in the Acb between HD-P and HD-M may be one of the factors involved in the development of psychiatric symptoms.

Brain research and clinical psychiatry: establishment of a psychiatry brain bank in Japan.

The Japan Agency of Medical Research and Development (AMED) has approved the budget for the 5-year project called Establishment of the JAPAN Brain Bank Network, which commenced in 2016. This project was established with the aim of storing brain tissue samples to enable research on the etiologies and mechanisms of psychiatric diseases, which would eventually improve standards of clinical treatment for these diseases. Japanese researchers in the field of biological psychiatry have historically depended on Western brain banks, particularly from Europe and the United States, which is regrettable. To remedy this situation and improve the Japanese research standards, attempts for establishing an autonomous Japanese brain bank are ongoing. Reviews of the previous attempts on elucidating the etiopathology of neuropsychiatric diseases reveal that rapid advances result from studies on tissue samples from diseased brains. For example, in the Kraepelin era, i.e. in 1900 years before and after, long-term, resolute research on diseased brain specimens ultimately led to the discoveries of entities such as Alzheimer disease and Lewy body disease. The recent advances in techniques of neuroimaging and molecular biology have resulted in a shift of interest from brain tissue analysis. However, the integration of findings of all these techniques is recommended going forward, with a shift in focus back to brain tissue analysis. The JAPAN Brain Bank Network project was launched under this setting. The success of this project largely depends on the will of patients and family members (for donating samples) as well as cooperation among many clinicians. In this paper, we provide a brief overview of the history of biological psychiatric research and related perspectives, which will hopefully encourage further studies that will help bridge the gap between clinical and biological research on psychiatric diseases.

The neuropathological investigation of the brain in a monkey model of autism spectrum disorder with ABCA13 deletion.

The precise biological etiology of autism spectrum disorder (ASD) remains unknown. In this study, we investigated the neuropathology of a monkey model of autism Human ABCA13 is the largest ABC transporter protein, with a length of 5058 amino acids and a predicted molecular weight of >450 kDa. However, the function of this protein remains to be elucidated. This protein is thought to be associated with major psychiatric disease. Using this monkey model of autism with an ABCA13 deletion and a mutation of 5HT2c, we neuropathologically investigated the changes in the neuronal formation in the frontal cortex. As a result, the neuronal formation in the cortex was found to be disorganized with regard to the neuronal size and laminal distribution in the ABCA13 deletion monkey. The catecholaminergic and GABAergic neuronal systems, serotoninergic neuronal formation (5HT2c) were also found to be impaired by an immunohistochemical evaluation. This study suggested that ABCA13 deficit induces the impairment of neuronal maturation or migration, and the function of the neuronal network. This protein might thus play a role in the neurodevelopmental function of the central nervous system and the dysfunction of this protein may be a pathophysiological cause of mental disorders including autism.

The neuropathological study of myelin oligodendrocyte glycoprotein in the temporal lobe of schizophrenia patients.

OBJECTIVE: Recent studies based on the neuroimaging analysis, genomic analysis and transcriptome analysis of the postmortem brain suggest that the pathogenesis of schizophrenia is related to myelin-oligodendrocyte abnormalities. However, no serious neuropathological investigation of this protein in the schizophrenic brain has yet been performed. In this study, to confirm the change in neuropathological findings due to the pathogenesis of this disease, we observed the expression of myelin-oligodendrocyte directly in the brain tissue of schizophrenia patients. METHODS: Myelin oligodendrocyte glycoprotein (MOG) was evaluated in the cortex of the superior temporal gyrus (STG) and the hippocampus in 10 schizophrenic and nine age- and sex-matched normal control postmortem brains. RESULTS: The expression of MOG was significantly lower in the middle layer of the neocortex of the STG and stratum lucidum of CA3 in the hippocampus in the long-term schizophrenic brains (patients with ≥30 years of illness duration) than in the age-matched controls. Furthermore, the thickness of MOG-positive fibre-like structures was significantly lower in both regions of the long-term schizophrenic brains than in the age-matched controls. CONCLUSION: These findings suggest that a long duration of illness has a marked effect on the expression of MOG in these regions, and that myelin-oligodendrocyte abnormalities in these regions may be related to the progressive pathophysiology of schizophrenia.

Neuropeptide Y neuronal network dysfunction in the frontal lobe of a genetic mouse model of schizophrenia.

Neuropeptide Y (NPY) has been found to play a critical role in various mental functions as a neurotransmitter and is involved in the development of schizophrenia, a particularly intractable psychiatric disease whose precise etiology remains unknown. Recent molecular biological investigations have identified several candidate genes which may be associated with this disease, including disrupted-in-schizophrenia 1 (DISC1). The role of DISC1 would involve neurogenesis and neuronal migration. However, the functional consequences of this gene defect have not yet been fully clarified in neuronal systems. In the present study, to clarify the neuropathological changes associated with the function of DISC1, we explored how DISC1 dysfunction can induce abnormalities in the NPY neuronal network in the central nervous system. We performed immunohistochemical analyses (including the observation of the distribution and density) of prefrontal cortex specimens from DISC1-knockout (KO) mice, which are considered to be a novel animal model of schizophrenia. We then evaluated the number and size of NPY-immunoreactive (NPY-IR) neurons and the length of NPY-IR fibers. The number of NPY-IR neurons and the length of the fibers were decreased in the prefrontal cortex of DISC1-KO mice. The decrease was particularly prominent in the superficial regions, and the distribution of NPY-IR neurons differed between wild-type and DISC1-KO mice. However, the size of the neurons in the cortices of the DISC1-KO and wild-type mice did not differ markedly. Our findings suggest that dysfunction of DISC1 may lead to the alteration of NPY neurons and neurotransmission issues in NPY-containing neuron systems, which seem to play important roles in both the mental function and neuronal development. DISC1 dysfunction may be involved in the pathogenesis of schizophrenia through the impairment of the NPY neuronal network.

An autopsy case of dementia with Lewy bodies clinically diagnosed to have a behavioral variant of frontotemporal dementia.

We herein report the case of a 75-year-old male who had shown many psychiatric symptoms, but whose autopsy disclosed the presence of dementia with Lewy bodies (DLB). When he was 70 years old, the patient had presented with stereotyped behavior, dietary changes, and a decline in social interpersonal conduct in clinical settings, and it was thought that these symptoms were consistent with a behavioral variant of frontotemporal dementia (bvFTD), and he lacked the core features of DLB. Nevertheless, this case was pathologically defined as the limbic type of DLB after he died at the age of 75 years. Looking retrospectively at the clinical course, it was considered that the following features were suggestive or supportive of DLB: neuroleptic sensitivity, autonomic symptoms, and psychiatric symptoms. It can be presumed that the bvFTD-like behavioral disturbances were caused by the severe Lewy pathology of the locus ceruleus (LC) and left anterior temporal region. The clinical symptoms of DLB might be more multifarious than has conventionally been thought, because the symptoms can be modified by the pathological spread of DLB within the brain. It is important to be aware of these possible symptoms of DLB so as not to overlook the diagnosis in the clinical setting.
.

Immunohistochemical evaluation of the GABAergic neuronal system in the prefrontal cortex of a DISC1 knockout mouse model of schizophrenia.

The etiology of schizophrenia remains unknown. However, using molecular biological techniques, some candidate genes have been identified that might be associated with the disease. One of these candidate genes, disrupted-in-schizophrenia 1 (DISC1), was found in a large Scottish family with multiple mental illnesses. The function of DISC1 is considered to be associated with axon elongation and neuron migration in the central nervous system, but the functional consequences of defects in this gene have not been fully clarified in brain neuronal systems. Dysfunction of the gamma-aminobutyric acid (GABA)ergic neuronal system is also considered to contribute to the pathogenesis of schizophrenia. Thus, to clarify the neuropathological changes associated with DISC1 dysfunction, we investigated the number and distribution of GABAergic neurons in the prefrontal cortex of DISC1 knockout mice. We immunohistochemically quantified the laminar density of GABAergic neurons using anti-parvalbumin and anti-calbindin D28k antibodies (markers of GABAergic neuronal subpopulations). We found that the densities of both parvalbumin- and calbindin-immunoreactive neurons in the anterior cingulate, medial prefrontal, and orbitofrontal cortices were markedly lower in DISC1 knockout mice than in wild-type mice. In addition, reductions in cell density were observed in layers II and III and the deep layers of the cortex. This reduction in GABAergic neuronal density was not associated with alterations in neuronal size. These findings suggest that disrupted GABAergic neuronal network formation due to a DISC1 deficit might be involved in the pathophysiology of schizophrenia.

An autopsy case of cortical superficial siderosis with persistent abnormal behavior.

In recent years, MRI has revealed cortical superficial siderosis (cSS), which exhibits hemosiderin deposition in only the cortical surface. However, the associations between the histological findings and clinical symptoms of cSS remain unclear. We herein report an autopsy case of a 75-year-old Japanese man with cSS with persistent abnormal behavior according to cognitive impairment, hallucination and delusion. At 73 years of age, the patient presented with unusual behavior that indicated auditory hallucination and delusion. One year later, he was admitted to the hospital for malignant lymphoma. On admission, cognitive impairment was detected by a screening test. Soon after hospitalization, he presented with active delirium including visual hallucination and delusion. The patient's excited behavior was improved by the administration of a major tranquilizer. However, the abnormal behavior and cognitive impairment persisted. At 75 years of age, he died of heart failure. A neuropathological investigation revealed hemosiderin depositions in the superficial layer of the cortex in the medial and lateral frontal lobe, the lateral temporal lobe, the parietal lobe, and the medial and lateral occipital lobe. Neuritic plaques and diffuse plaques were extensively observed, which corresponded to Braak stage C and CERAD B, although NFTs were observed that corresponded to Braak stage II. Cortical amyloid angiopathy was not observed in any regions. Ischemic change of brain was also mild. Our report suggests that localized deposition of hemosiderin in the cortex might affect the manifestation of cognitive impairments and hallucination. Further clinicopathological studies are needed to clarify the clinical manifestations of patients with cSS.

Hypochondriasis as an early manifestation of dementia with Lewy bodies: an autopsied case report.

Discrepancies between clinical and pathological diagnoses of dementia with Lewy bodies (DLB) may occur because the full disease progression remains unclear, especially during the early stage. Herein, we report the case of a 78-year-old Japanese man with hypochondriasis who had autopsy-confirmed limbic-type DLB pathology. He exhibited no core clinical features of DLB. We attempted to identify the clinicopathological correlations in the early stages of DLB. At the age of 77, he became hypochondriacal and exhibited progressive cognitive decline after the death of his wife. He was concerned about his poor physical condition, but hospital examinations did not identify any overtly abnormal findings. At 78 years of age, he consulted a neurologist with complaints of facial numbness and irritability. Neurological examination revealed no overt abnormality, and he scored 21 points on the Mini-Mental State Examination. Magnetic resonance imaging of the brain showed mild bilateral ventricular enlargement. The patient was clinically diagnosed as having possible Alzheimer's disease. Approximately 1 month after his consult, he died of acute pneumonia in a psychiatric hospital to which he had been admitted for severe aggressive behaviour. He exhibited no core clinical features pointing towards a clinical diagnosis of DLB. Neuropathological investigation revealed limbic-type Lewy body disease with concurrent minimum Alzheimer-type pathology, which corresponds to high-likelihood DLB pathology based on the Third Consortium DLB pathological criteria. The patient had minimum nigral degeneration, which is consistent with the absence of parkinsonism. This autopsied case suggests that some DLB patients exhibit hypochondriasis in the early stage of the disease, even if they lack the core clinical features of DLB.

Catecholaminergic neuronal network dysfunction in the frontal lobe of a genetic mouse model of schizophrenia.

BACKGROUND: The precise aetiology of schizophrenia remains unclear. The neurodevelopmental hypothesis of schizophrenia has been proposed based on the accumulation of genomic or neuroimaging studies. OBJECTIVE: In this study, we examined the catecholaminergic neuronal networks in the frontal cortices of disrupted-in-schizophrenia 1 (DISC1) knockout (KO) mice, which are considered to be a useful model of schizophrenia. METHODS: Six DISC1 homozygous KO mice and six age-matched littermates were used. The animals' brains were cut into 20-µm-thick slices, which were then immunohistochemically stained using an anti-tyrosine hydroxylase (TH) monoclonal antibody. RESULTS: The TH-immunopositive fibres detected in the orbitofrontal cortices of the DISC1 KO mice were significantly shorter than those seen in the wild-type mice. CONCLUSION: These neuropathological findings indicate that the hypofrontal symptoms of schizophrenia are associated with higher mental function deficiencies or cognitive dysfunction such as a loss of working memory.