High prevalence of neuronal surface autoantibodies associated with cognitive deficits in cancer patients

Initial screening for neuronal autoantibodies and their putative impact on survival in patients with small-cell lung cancer

INTRODUCTION

Small-cell lung cancer (SCLC) may be associated with neuronal autoantibodies and paraneoplastic neurological syndromes. It has been suggested that neuronal autoantibodies, especially antineuronal nuclear antibody type 1 (Hu) autoantibodies, are associated with longer survival of patients with SCLC. The objective of this study was to determine the frequency and distribution of neuronal autoantibodies at the time of diagnosis of SCLC patients and assess survival rates in relation to autoimmunity.

METHODS

In this retrospective study, serum from 40 patients with biopsy-proven SCLC at the time of diagnosis was studied prior to treatment. The sera originated from a cancer registry at the Oncology Department, Vejle Hospital from 2007 to 2010. The sera were analyzed blindly to clinical status for the presence of neuronal autoantibodies. Medical records were reviewed for neurological symptoms.

RESULTS

Neuronal autoantibodies were detected in 22/40 (55%) of the SCLC patients. A broad range of neurological symptoms was recorded in 28/40 (70%) patients, of which 14/28 (50%) were positive for neuronal autoantibodies. The most frequently detected autoantibodies were Hu (7/40, 17.5%) followed by GAD65 (6/22, 15.0%). Striational and P/Q- or N-type voltage-gated calcium channel antibodies were less common, with each found in five patients (12.5%). Eight patients (20%) had coexisting autoantibodies. Autoantibody-positivity was not associated with survival.

CONCLUSION

Neuronal autoantibodies were at time of diagnosis found in approximately half of the treatment-naïve SCLC patients. Neither autoantibody positivity at diagnosis nor neurological manifestations correlated with survival and their clinical importance requires further studies in larger, prospective cohorts.

Prevalence and Factor Associated with Anti-N-Methyl-D-Aspartate Receptor Encephalitis Among Patients with Medical Conditions: A Systematic Review and Meta-Analysis

BACKGROUND

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe autoimmune encephalitis due to immune production of anti-NMDAR antibodies against the NR1 subunit of the NMDA receptor which is present throughout the central nervous system. This condition had been reported to be prevalent in patients with certain medical conditions; however so far, there have been limited systematic reviews and meta-analyses on the prevalence and factors associated.

OBJECTIVE

This study was to determine the prevalence and factors associated with anti-NMDAR encephalitis among affected patients.

MATERIAL AND METHODS

The protocol of this study has been registered (2019: CRD42019142002) with the International Prospective Register of Systematic Reviews (PROSPERO). The primary outcome was the incidence or prevalence of anti-NMDAR encephalitis and secondary outcomes were factors associated with anti-NMDAR encephalitis.

RESULTS

There were 11 studies and a total of 873 million patients taken from high-risk populations across 11 countries that were included in the primary analysis. The overall pooled prevalence of anti-NMDAR encephalitis among patients with medical conditions was 7.0% (95% CI = 4.4, 9.6). Those with first episode of psychosis or schizophrenia were at a higher risk of developing anti-NMDAR encephalitis with an odds ratio of 5.976 (95% CI = 1.122, 31.825).

CONCLUSION

We found that almost one-tenth of patients with medical conditions had anti-NMDAR encephalitis; particularly those with first episode of psychosis or schizophrenia were among the high-risk medical conditions.

Overview of Paraneoplastic Autoantibody-Mediated Cognitive Impairment and Behavioral Changes: A Narrative Review

Cognitive dysfunction and behavioral change can be some of the manifestations of cancer, occurring as a part of paraneoplastic neurological syndrome, most commonly in small cell lung cancer. Paraneoplastic limbic encephalitis is the leading cause of cognitive disturbance and abnormal behavior in paraneoplastic syndromes, which is usually autoantibody-mediated. Autoantibodies are the main contributors to the development of cognitive dysfunction and behavioral change in cancer patients, with studies suggesting a higher liability for antibody-positive cancer patients to be affected. Anti-NMDAR and anti-AMPAR are antibodies targeted against surface antigens, manifesting predominantly as memory disturbance, abnormal behavior, psychiatric symptoms, and seizures. Other surface antigen-targeted antibodies include anti-GABA, anti-CASPR2, and anti-LGI1, which were shown to have cognitive function impairment and abnormal behavior as some of the main presentations, predominantly affecting memory. Cognitive deterioration and changes in behavior were also relatively common with some of the intracellular antigen-targeted antibodies, including anti-Hu, anti-SOX1, anti-PCA2, and anti-Zic2. Affected behavior and cognition, however, were reported less commonly in other paraneoplastic antibodies against intracellular antigens (anti-Yo, anti-GAD, anti-Ma2, anti-Ri, anti-CV2, and anti-KLHL11). Our article will provide a comprehensive review of the clinical manifestations of cognitive impairment and behavioral changes among cancer patients who develop paraneoplastic syndrome. Additionally, this review will discuss the role of specific paraneoplastic autoantibodies and the clinical spectrum linked to each separately.

Depressive symptoms and anti-N-methyl-D-aspartate-receptor GluN1 antibody seropositivity in the PROSpective cohort with incident stroke

Background

Anti-NMDA-receptor GluN1 antibodies (NMDAR1-abs) are present in an autoimmune encephalitis with severe neuropsychiatric symptoms. We aimed to estimate the impact of serum NMDAR1-abs on depressive symptoms years after first-ever ischemic stroke (IS).

Methods

Data were used from the PROSpective Cohort with Incident Stroke-Berlin (PROSCIS-B; NCT01363856). Serum NMDAR1-abs (IgM/IgA/IgG) were measured within 7 days after IS using cell-based assays. We defined seropositivity as titers ≥1:10, thereof low titers as ≤1:100 and high titers as >1:100. We used the Center for Epidemiological Studies-Depression (CES-D) scale to measure depressive symptoms at year one, two and three following IS. We calculated crude and confounder adjusted weighted generalized linear models to quantify the impact of NMDAR1-abs on CES-D assessed at three annual time-points.

Results

NMDAR1-abs were measured in 583 PROSCIS-B IS patients (mean age = 67 [SD = 13]; 42%female; median NIHSS = 2 [IQR = 1-4]) of whom 76 (13%; IgM: n = 49/IgA: n = 43/IgG: n = 2) were seropositive, 55 (9%) with low and 21 (4%) with high titers. CES-D regarded over all follow-up time-points was higher in seropositive patients (βcrude = 2.56 [95%CI = -0.34 to 5.45]; βadjusted = 2.26 [95%CI = -0.68 to 5.20]) and effects were highest in patients with high titer (low titers: βcrude = 1.42 [95%CI = -1.79 to 4.62], βadjusted = 0.53 [95%CI = -2.47 to 3.54]; high titers: βcrude = 5.85 [95%CI = 0.20 to 11.50]; βadjusted = 7.20 [95%CI = 0.98 to 13.43]).

Conclusion

Patients with serum NMDAR1-abs (predominantly IgM&IgA) suffer more severe depressive symptoms after mild-to-moderate IS compared to NMDAR1-abs seronegative patients.

Autoantibody profiles in patients with immune checkpoint inhibitor-induced neurological immune related adverse events

Background

Neurological immune-related adverse events (irAE-n) are severe and potentially fatal toxicities of immune checkpoint inhibitors (ICI). To date, the clinical significance of neuronal autoantibodies in irAE-n is poorly understood. Here, we characterize neuronal autoantibody profiles in patients with irAE-n and compare these with ICI-treated cancer patients without irAE-n.

Methods

In this cohort study (DRKS00012668), we consecutively collected clinical data and serum samples of 29 cancer patients with irAE-n (n = 2 pre-ICI, n = 29 post-ICI) and 44 cancer control patients without irAE-n (n = 44 pre- and post-ICI). Using indirect immunofluorescence and immunoblot assays, serum samples were tested for a large panel of neuromuscular and brain-reactive autoantibodies.

Results

IrAE-n patients and controls received ICI treatment targeting programmed death protein (PD-)1 (61% and 62%), programmed death ligand (PD-L)1 (18% and 33%) or PD-1 and cytotoxic T-lymphocyte-associated protein (CTLA-)4 (21% and 5%). Most common malignancies were melanoma (both 55%) and lung cancer (11% and 14%). IrAE-n affected the peripheral nervous system (59%), the central nervous system (21%), or both (21%). Prevalence of neuromuscular autoantibodies was 63% in irAE-n patients, which was higher compared to ICI-treated cancer patients without irAE-n (7%, p <.0001). Brain-reactive autoantibodies targeting surface (anti-GABA_BR, -NMDAR, -myelin), intracellular (anti-GFAP, -Zic4, -septin complex), or unknown antigens were detected in 13 irAE-n patients (45%). In contrast, only 9 of 44 controls (20%) presented brain-reactive autoantibodies before ICI administration. However, seven controls developed de novo brain-reactive autoantibodies after ICI initiation, therefore, prevalence of brain-reactive autoantibodies was comparable between ICI-treated patients with and without irAE-n (p = .36). While there was no clear association between specific brain-reactive autoantibodies and clinical presentation, presence of at least one of six selected neuromuscular autoantibodies (anti-titin, anti-skeletal muscle, anti-heart muscle, anti-LRP4, anti-RyR, anti-AchR) had a sensitivity of 80% (95% CI 0.52-0.96) and a specificity of 88% (95% CI 0.76-0.95) for the diagnosis of myositis, myocarditis, or myasthenia gravis.

Conclusion

Neuromuscular autoantibodies may serve as a feasible marker to diagnose and potentially predict life-threatening ICI-induced neuromuscular disease. However, brain-reactive autoantibodies are common in both ICI-treated patients with and without irAE-n, hence, their pathogenic significance remains unclear.

Serum anti-NMDA-receptor antibodies and cognitive function after ischemic stroke (PROSCIS-B)

Objective

We aimed to investigate whether serum anti-N-methyl-D-aspartate-receptor GluN1 (previously NR1) antibody (NMDAR1-abs) seropositivity impacts cognitive function (CF) in the long term following ischemic stroke.

Methods

Data were used from the PROSpective Cohort with Incident Stroke-Berlin. NMDAR1-abs (IgM/IgA/IgG) were measured with cell-based assays from serum obtained within 7 days after the first-ever stroke. Seropositivity was defined as titers ≥ 1:10, low titers as ≤ 1:100 and high titers as > 1:100. We assessed CF at 1, 2 and 3 years after stroke with the Telephone Interview for Cognitive Status-modified (TICS-m) and used crude and propensity score adjusted inverse probability weighted generalized linear models to estimate the impact of NMDAR1-abs serostatus on TICS-m.

Results

Data on NMDAR1-abs (median day of sampling = 4[IQR = 2–5]) were available in 583/621 PROSCIS-B patients (39% female; median NIHSS = 2[IQR = 1–4]; median MMSE = 28[IQR:26–30]), of whom 76(13%) were seropositive (IgM: n = 48/IgA: n = 43/IgG: n = 2). Any NMDAR1-abs seropositivity had no impact on TICS-m compared to seronegative patients (βcrude = 0.69[95%CI = – 0.84 to 2.23]; βadjusted = 0.65[95%CI = – 1.00 to 2.30]). Patients with low titers scored better on TICS-m compared to seronegative patients (βcrude = 2.33[95%CI = 0.76 to 3.91]; βadjusted = 2.47[95%CI = 0.75 to 4.19]); in contrast, patients with high titers scored lower on TICS-m (βcrude =  –2.82[95%CI = – 4.90 to – 0.74], βadjusted = – 2.96[95%CI = – 5.13 to – 0.80]), compared to seronegative patients.

Conclusion

In our study, NMDAR1-abs seropositivity did not affect CF over 3 years after a first mild to moderate ischemic stroke. CF differed according to NMDAR1-abs serum titer, with patients with high NMDAR1-abs titers having a less favorable cognitive outcome compared to seronegative patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11203-x.

Chronic presence of blood circulating anti-NMDAR1 autoantibodies impairs cognitive function in mice

High titers of anti-NMDAR1 autoantibodies in brain cause anti-NMDAR1 encephalitis that displays psychiatric symptoms of schizophrenia and/or other psychiatric disorders in addition to neurological symptoms. Low titers of anti-NMDAR1 autoantibodies are reported in the blood of a subset of the general human population and psychiatric patients. Since ~0.1–0.2% of blood circulating antibodies cross the blood-brain barriers and antibodies can persist for months and years in human blood, it is important to investigate whether chronic presence of these blood circulating anti-NMDAR1 autoantibodies may impair human cognitive functions and contribute to the development of psychiatric symptoms. Here, we generated mice carrying low titers of anti-NMDAR1 autoantibodies in blood against a single antigenic epitope of mouse NMDAR1. Mice carrying the anti-NMDAR1 autoantibodies are healthy and display no differences in locomotion, sensorimotor gating, and contextual memory compared to controls. Chronic presence of the blood circulating anti-NMDAR1 autoantibodies, however, is sufficient to impair T-maze spontaneous alternation in the integrity of blood-brain barriers across all 3 independent mouse cohorts, indicating a robust cognitive deficit in spatial working memory and/or novelty detection. Our studies implicate that chronic presence of low titers of blood circulating anti-NMDAR1 autoantibodies may impair cognitive functions in both the general healthy human population and psychiatric patients.

Association Between Neuronal Autoantibodies and Cognitive Impairment in Patients With Lung Cancer

Importance

Paraneoplastic neurological syndromes are associated with neuronal autoantibodies, and some of these autoantibodies are associated with neuropsychological symptoms. The most common underlying tumor is lung cancer. The association of neuronal autoantibodies with cognitive deficits has not been systematically investigated in patients with small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).

Objective

To assess the frequency of neuronal autoantibodies in patients with lung cancer and analyze their association with cognitive function.

Design, Setting, and Participants

This prospective, cross-sectional study included 167 patients with lung cancer (both SCLC and NSCLC) recruited at a single lung cancer center in Berlin, Germany, between June 2015 and April 2016. Detailed neuropsychological testing was performed in a carefully selected subgroup of 97 patients (from which patients with potential confounding factors were excluded). Investigators were blinded to patients' autoantibody status and cognitive test results. Data were analyzed from May 2016 to December 2019.

Main Outcomes and Measures

Prevalence of neuronal autoantibodies and their association with cognitive impairment. The evaluation of autoantibodies as potential risk factors for cognitive impairment was performed using bayesian logistic regression models.

Results

Among 167 patients with lung cancer (median age, 66.0 years [interquartile range, 59.0-72.0 years]; 105 men [62.9%]), 127 had NSCLC, and 40 had SCLC. Brain-directed autoantibodies were detected in 61 of 167 patients (36.5%); 33 patients (19.8%) had known autoantibodies and 28 patients (16.8%) had autoantibodies against currently unknown antigens that were detected through immunohistochemical analysis. Cognitive impairment was found in 65 of 97 patients (67.0%). Among patients with SCLC, the odds of cognitive impairment for those with any autoantibodies was 11-fold higher (odds ratio [OR], 11.0; 95% credible interval [CrI], 1.2-103.6) than that of autoantibody-negative patients, and the increased odds were independent of age, sex, and neurological deficit. Among patients with NSCLC, those with immunoglobin A autoantibodies targeting the N-methyl-d-aspartate receptor had a relevantly increased odds of verbal memory deficits (OR, 182.8; 95% CrI, 3.1-10 852.4). Autoantibodies against currently unknown antigens were also associated with increased odds of cognitive impairment (OR, 2.8; 95% CrI, 0.6-12.1).

Conclusions and Relevance

In this prospective, cross-sectional study, more than one-third of patients with lung cancer had neuronal autoantibodies that were found to be associated with cognitive impairment. These autoantibodies might represent a potentially treatable mechanism of immune-mediated cognitive impairment among patients with lung cancer.

Clinical, cognitive and neuroanatomical associations of serum NMDAR autoantibodies in people at clinical high risk for psychosis

Serum neuronal autoantibodies, such as those to the NMDA receptor (NMDAR), are detectable in a subgroup of patients with psychotic disorders. It is not known if they are present before the onset of psychosis or whether they are associated with particular clinical features or outcomes. In a case-control study, sera from 254 subjects at clinical high risk (CHR) for psychosis and 116 healthy volunteers were tested for antibodies against multiple neuronal antigens implicated in CNS autoimmune disorders, using fixed and live cell-based assays (CBAs). Within the CHR group, the relationship between NMDAR antibodies and symptoms, cognitive function and clinical outcomes over 24 month follow-up was examined. CHR subjects were not more frequently seropositive for neuronal autoantibodies than controls (8.3% vs. 5.2%; OR = 1.50; 95% CI: 0.58-3.90). The NMDAR was the most common target antigen and NMDAR IgGs were more sensitively detected with live versus fixed CBAs (p < 0.001). Preliminary phenotypic analyses revealed that within the CHR sample, the NMDAR antibody seropositive subjects had higher levels of current depression, performed worse on the Rey Auditory Verbal Learning Task (p < 0.05), and had a markedly lower IQ (p < 0.01). NMDAR IgGs were not more frequent in subjects who later became psychotic than those who did not. NMDAR antibody serostatus and titre was associated with poorer levels of functioning at follow-up (p < 0.05) and the presence of a neuronal autoantibody was associated with larger amygdala volumes (p < 0.05). Altogether, these findings demonstrate that NMDAR autoantibodies are detectable in a subgroup of CHR subjects at equal rates to controls. In the CHR group, they are associated with affective psychopathology, impairments in verbal memory, and overall cognitive function: these findings are qualitatively and individually similar to core features of autoimmune encephalitis and/or animal models of NMDAR antibody-mediated CNS disease. Overall the current work supports further evaluation of NMDAR autoantibodies as a possible prognostic biomarker and aetiological factor in a subset of people already meeting CHR criteria.

Paraneoplastic Neurological Syndromes: Study of Prevalence in a Province of the Lombardy Region, Italy

Paraneoplastic neurological syndromes (PNSs) are a heterogeneous group of rare immune-mediated diseases associated with cancer. The aim of this study was to investigate the prevalence of PNSs in the province of Brescia. PNS prevalence was calculated using the Lombardy regional hospital admission records from 1998 to 2003. We used the website "Epidemiologic and Economic Atlas of Hospital Activities in Lombardy" and the "International Statistical Classification of Diseases and Related Health Problems". In the province of Brescia, we found 54 cases of PNSs, 29 with subacute neuropathies, five with paraneoplastic cerebellar degeneration and 20 with encephalomyelitis. Peripheral nervous system diseases were the most frequent neurological disorders. In Lombardy, the number of PNS patients admitted was 322 (133 with encephalomyelitis, 21 with paraneoplastic cerebellar degeneration, 166 with polyneuropathies and two with optic degeneration). In Lombardy, the prevalence of PNSs was 25 in 100,000 hospital admissions and 5.92 in 100,000 for the Lombardy population. Our results show a discrete presence of PNS patients in the province of Brescia and in the Lombardy region as a whole.

Cognitive impact of neuronal antibodies: encephalitis and beyond

Cognitive dysfunction is a common feature of autoimmune encephalitis. Pathogenic neuronal surface antibodies are thought to mediate distinct profiles of cognitive impairment in both the acute and chronic phases of encephalitis. In this review, we describe the cognitive impairment associated with each antibody-mediated syndrome and, using evidence from imaging and animal studies, examine how the nature of the impairment relates to the underlying neuroimmunological and receptor-based mechanisms. Neuronal surface antibodies, particularly serum NMDA receptor antibodies, are also found outside of encephalitis although the clinical significance of this has yet to be fully determined. We discuss evidence highlighting their prevalence, and association with cognitive outcomes, in a number of common disorders including cancer and schizophrenia. We consider mechanisms, including blood-brain barrier dysfunction, which could determine the impact of these antibodies outside encephalitis and account for much of the clinical heterogeneity observed.

Serum Systemic Autoantibodies in Anti-N-Methyl-D-Aspartate Receptor Encephalitis

Objective: The aim of this retrospective study was to investigate the relationship between serum systemic autoantibodies and anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.

Methods: Thirty-nine patients with anti-NMDAR encephalitis were examined for serum systemic autoantibodies (antinuclear antibodies, extractable nuclear antigen autoantibodies, rheumatoid factors, and anti-neutrophil cytoplasmic antibodies), in comparison with 39 neuromyelitis optica spectrum disorder (NMOSD) and 78 healthy controls. Clinical features, cerebrospinal fluid characteristics, and outcomes were compared between the two subgroups of anti-NMDAR patients with positive and negative systemic autoantibodies, respectively.

Results: Anti-NMDAR encephalitis patients had higher frequency of positive serum systemic autoantibodies than healthy controls (23.1 vs. 2.6%, p = 0.001) and lower frequency than NMOSD (23.1 vs. 48.7%, p = 0.018). No patients were diagnosed comorbidities with non-organ-specific autoimmune diseases. Consciousness disturbance was more frequent in autoantibodies positive group than in the negative group (88.9 vs. 40.0%, p = 0.02). Autoantibody positive group had a poorer outcome than autoantibody negative group (55.6 vs. 86.7%, p = 0.043). There was a negative correlation between serum autoantibodies and outcomes in anti-NMDAR encephalitis patients (r = −0.325, p = 0.044).

Conclusion: Our data demonstrated serum systemic autoantibodies were more frequent in anti-NMDAR encephalitis patients than in healthy controls and less frequent than NMOSD, which were associated with higher severity of disease.

Neuronal autoantibodies associated with cognitive impairment in melanoma patients

BACKGROUND

Cancer-related cognitive impairment is an important complication in cancer patients, yet the underlying mechanisms remain unknown. Over the last decade, the field of paraneoplastic neurological syndromes has been dramatically changed by the discovery of new neuronal autoantibodies, some of them associated with cognitive impairment. We aimed to assess the prevalence of neuronal autoantibodies in melanoma patients and their association with neurological and cognitive dysfunction.

PATIENTS AND METHODS

A total of 157 consecutive melanoma patients with a median age of 63 years were recruited at the Department of Dermatology, Charité-Universitätsmedizin Berlin and tested for neuronal autoantibodies. A comprehensive neuropsychological assessment was carried out in a selected subgroup of 84 patients after exclusion of patients with confounding factors for a cognitive dysfunction, including brain metastases, relevant medication, and neurological disorders.

RESULTS

Neuronal autoantibodies were found in 22.3% of melanoma patients. The most frequent antibodies were IgA/IgM anti-NMDAR antibodies. Applying the International Cognition and Cancer Task Force criteria, 36.9% had cognitive impairment, however, with a threefold higher odds in antibody-positive compared with antibody-negative patients (57.1% versus 30.2%, OR = 3.1, 95% CI: 1.1 to 8.6; P = 0.037). In patients with anti-NMDAR antibodies, this impairment increased with higher antibody titers (P = 0.007). Antibody-positive patients had a significantly impaired overall cognitive performance (z-value: -0.38 ± 0.69 versus 0.00 ± 0.56; P = 0.014) as well as significant impairments in tests of memory, attention, and executive function. In a multiple linear regression analysis, autoantibodies were an independent risk factor for cognitive impairment (B = -0.282; 95% CI: -0.492 to -0.071; P = 0.009). Autoantibody seropositivity was associated with immune checkpoint inhibitor treatment and a history of autoimmune diseases.

CONCLUSIONS

A large number of melanoma patients harbor neuronal autoantibodies that are associated with significant cognitive impairment affecting memory, attention, and executive function. Neuronal autoantibodies might represent a pathophysiological factor and possible biomarker in the development of cancer-related cognitive impairment.

Autoantibodies against N-methyl-d-aspartate receptor 1 in health and disease

Purpose of review

Humoral autoimmunity has gained highest interest in neurology and psychiatry. Despite numerous recent articles on this hot topic, however, the biological significance of natural autoantibodies (AB) and the normal autoimmune repertoire of mammals remained quite obscure. AB may contribute to disorder-relevant phenotypes and are even believed to induce diseases themselves, but the circumstances under which AB become pathogenic are not fully understood. This review will focus on the highly frequent AB against the N-methyl-d-aspartate receptor 1 (NMDAR1-AB) as an illustrating example and provide a critical overview of current work (please note that the new nomenclature, GluN1, is disregarded here for consistency with the AB literature). In particular, it will demonstrate how little is known at this point and how many conclusions are drawn based on small numbers of individuals, fragmentary experimental approaches or missing controls.

Recent findings

NMDAR1-AB were investigated by clinicians world-wide with numerous small studies and case reports appearing yearly. Many publications were on ‘anti-NMDAR encephalitis’ cases or tried to separate those from other NMDAR1-AB associated conditions. Original exclusivity claims (e.g. electroencephalogram, EEG or functional magnetic resonance imaging, fMRI findings) turned out not to be exclusive for ‘anti-NMDAR encephalitis’. Systematic analyses of representative NMDAR1-AB positive sera of all immunoglobulin (Ig) classes showed comparable distribution of different epitopes, often polyspecific/polyclonal, across health and disease. Sophisticated imaging tools provided findings on synapse trafficking changes induced by NMDAR1-AB from psychotic subjects but still lack epitope data to support any claimed disorder link. Persistently high titers of NMDAR1-AB (IgG) in immunized mice with open blood–brain barrier (BBB)-induced psychosis-like symptoms but failed to induce inflammation in the brain. Knowledge on peripheral NMDAR, for example in the immune system, and on potential inducers of NMDAR1-AB is only slowly increasing.

Summary

The present knowledge on the (patho) physiological role of NMDAR1-AB is very limited and still characterized by adamant rumors. Much more experimental work and more solid and informative clinical reports, including large numbers of subjects and adequate control groups, follow-up investigations and interdisciplinary approaches will be necessary to obtain a better understanding of the significance of humoral autoimmunity in general (in focus here: NMDAR1-AB) and its disease-relevance in particular.

Brain metastases and treatment: multiplying cognitive toxicities

INTRODUCTION

Thirty per cent of cancer patients develop brain metastases, with multiple combination or sequential treatment modalities available, to treat systemic or central nervous system (CNS) disease. Most patients experience toxicities as a result of these treatments, of which cognitive impairment is one of the adverse events most commonly reported, causing major impairment of the patient's quality of life. Areas covered: This article reviews the role of cancer treatments in cognitive decline of patients with brain metastases: surgery, radiotherapy, chemotherapy, targeted therapies, immunotherapies and hormone therapy. Pathological and molecular mechanisms, as well as future directions for limiting cognitive toxicities are also presented. Other causes of cognitive impairment in this population are discussed in order to refine the benefit-risk balance of each treatment modality. Expert opinion: Cumulative cognitive toxicity should be taken into account, and tailored to the patient's cognitive risk in the light of the expected survival benefit. Standardization of cognitive assessment in this context is needed in order to better appreciate each treatment's responsibility in cognitive impairment, keeping in mind disease itself impacts cognition in this context.

The Role of Cannabis within an Emerging Perspective on Schizophrenia

Background: Approximately 0.5% of the population is diagnosed with some form of schizophrenia, under the prevailing view that the pathology is best treated using pharmaceutical medications that act on monoamine receptors. Methods: We briefly review evidence on the impact of environmental forces, particularly the effect of autoimmune activity, in the expression of schizophrenic profiles and the role of Cannabis therapy for regulating immunological functioning. Results: A review of the literature shows that phytocannabinoid consumption may be a safe and effective treatment option for schizophrenia as a primary or adjunctive therapy. Conclusions: Emerging research suggests that Cannabis can be used as a treatment for schizophrenia within a broader etiological perspective that focuses on environmental, autoimmune, and neuroinflammatory causes of the disorder, offering a fresh start and newfound hope for those suffering from this debilitating and poorly understood disease.