Psychiatric symptoms in anti glutamic acid decarboxylase associated limbic encephalitis in adults: a systematic review

[Autoimmune encephalitis: psychiatric aspects]

Autoimmune encephalitis is a group of diseases researched by both neurologists and psychiatrists. Despite a large number of studies and practical recommendations, the differential diagnosis and early diagnostics still remains an important issue. The most difficult to diagnose are cases that debut as mental disorders and/or occur without neurological symptoms. The literature review presents the current state of the problem with an emphasis on the practice of a psychiatrist.

Anti-glutamic acid decarboxylase antibody screening in first-episode psychosis

OBJECTIVE

The Royal Australian and New Zealand College of Psychiatrists recommends screening for a range of antibodies in first-episode psychosis, including anti-glutamic acid decarboxylase antibodies. Glutamic acid decarboxylase antibody-associated encephalitis occurs with high antibody titres and may cause cognitive dysfunction, seizures and psychiatric symptoms. However, glutamic acid decarboxylase antibodies are more frequently found in lower titre in association with other autoimmune disorders (such as diabetes mellitus type 1) and in healthy individuals. The utility of testing unselected populations of consumers with psychosis is unclear. The psychiatric manifestations of this disorder are also poorly described.

METHODS

First, systematic review of cohort and case-control studies that tested for IgG glutamic acid decarboxylase antibodies in psychiatric populations was conducted. Random-effects meta-analysis of odds ratio for antibody positivity in cases with psychosis and controls assessed prevalence. Second, literature review of all published cases and case series of glutamic acid decarboxylase antibody-associated limbic encephalitis was assessed for frequency and description of psychotic symptoms.

RESULTS

There were 17 studies, in which 2754 individuals with psychotic disorders were tested for glutamic acid decarboxylase IgG antibodies. Thirty-one consumers with psychosis (0.7%) had positive glutamic acid decarboxylase antibodies compared to 24 controls (1.0%), all at low titre and not fulfilling diagnostic criteria for autoimmune encephalitis. Meta-analysis found no significant difference in rates of glutamic acid decarboxylase antibody positivity (odds ratio = 1.8, 95% confidence interval: [0.90, 3.63]). Literature review found 321 cases of glutamic acid decarboxylase antibody-associated limbic encephalitis, with psychosis in 15 (4.3%) cases. Clinical screening would have identified all cases that presented to psychiatric services.

CONCLUSION

Glutamic acid decarboxylase antibodies were uncommon in consumers with psychosis, with no significant difference in prevalence from controls and no cases of encephalitis identified. In cases with established glutamic acid decarboxylase antibody-associated limbic encephalitis, psychotic symptoms were uncommon and identifiable by clinical assessment. Targeted antibody testing guidelines should be further considered.

Review and meta-analysis of neuropsychological findings in autoimmune limbic encephalitis with autoantibodies against LGI1, CASPR2, and GAD65 and their response to immunotherapy

OBJECTIVES

It is assumed that autoimmune limbic encephalitis (ALE) demonstrates distinct neuropsychological manifestations with differential responses to immunotherapy according to which associated autoantibody (AAB), if any, is identified. Towards investigating whether this is the case, this study aims to summarize respective findings from the primary literature on ALE with AABs binding to cell surface neural antigens and ALE with AABs against intracellular neural antigens.

METHODS

We chose ALE with AABs against leucine-rich, glioma inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) as the most frequent cell surface membrane antigens, and ALE with AABs to Embryonic Lethal, Abnormal Vision, Like 1 (ELAVL) proteins (anti-Hu) and glutamic acid decarboxylase 65 (GAD65) as the most frequent intracellular neural antigens. The PubMed and Scopus databases were searched on March 1st, 2021 for neuropsychological test and -screening data from patients with ALE of these AAB-types. Findings were reviewed according to AAB-type and immunotherapy status and are presented in a review section and are further statistically evaluated and presented in a meta-analysis section in this publication.

RESULTS

Of the 1304 initial hits, 32 studies on ALE with AABs against LGI1, CASPR2, and GAD65 reporting cognitive screening data could be included in a review. In ALE with AABs against LGI1, CASPR2 and GAD65, memory deficits are the most frequently reported deficits. However, deficits in attention and executive functions including working memory, fluency, and psychological function have also been reported. This review shows that ALE patients with AABs against both LGI1 and CASPR2 show higher percentages of neuropsychological deficits compared to ALE patients with AABs against GAD65 before and after initiation of immunotherapy. However, the methodologies used in these studies were heterogenous, and longitudinal studies were not comparable. Moreover, 21 studies including ALE patients with AABs against LGI1 and GAD65 were also suitable for meta-analysis. No suitable study on ALE with AABs against ELAVL proteins could be identified. Meta-Analyses could be executed for cognitive screening data and only partially, due to the small number of studies. However, in statistical analysis no consistent effect of AAB or immunotherapy on performance in cognitive screening tests could be found.

CONCLUSION

Currently, there is no definite evidence supporting the notion that different AAB-types of ALE exhibit distinct neuropsychological manifestations and respond differently to immunotherapy. Overall, we could not identify evidence for any effect of immunotherapy on cognition in ALE. More systematic, in-depth and longitudinal neuropsychological assessments of patients with different AAB-types of ALE are required in the future to investigate these aspects.

Case report: Anti-GAD65 antibody-associated autoimmune encephalitis following HPV vaccination

Human papillomavirus (HPV) infection is a sexually transmitted disease that may lead to cervical cancer. HPV vaccines have been implemented widely to prevent this. While generally few complications of vaccination are reported, there have been occasional reports of adverse reactions post-vaccination. The safety profile of the HPV vaccine is reassuring. However, since its introduction, several serious post-vaccination central nervous system complications have been reported; however, causality has not been established. Herein, we describe a 39-year-old woman who developed seizures and experienced a rapid decline in memory shortly after her first dose of the HPV vaccine. Cranial magnetic resonance imaging and cerebrospinal fluid analysis were performed, and the patient was diagnosed with anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody-associated autoimmune encephalitis. She responded well to high-dose glucocorticoids. Four-month follow-up revealed full recovery and absence of recurrence. Since the HPV vaccine is administered worldwide, this case should raise clinicians' awareness regarding the possible CNS complications related to vaccinations, such as anti-GAD65 antibody-associated AE.

Nonparaneoplastic Anti-GAD Limbic Encephalitis: Seizure Outcome and Long-term Neuropsychological Follow-up After Immunotherapy

Antibodies against glutamate decarboxylase (GAD-Abs), especially GAD65 antibodies, are associated with limbic encephalitis (LE) manifested by temporal lobe epilepsy and neuropsychological deficits. We present the case of a 42-year-old Greek woman with nonparaneoplastic anti-GAD LE, discussing the therapeutic management and highlighting the role of neuropsychological assessment. The patient underwent functional and structural brain studies and was investigated longitudinally over a 6-year period with a battery of neuropsychological tests that were designed to document her intellectual function and verbal and visual memory. The patient suffered from refractory temporal-impaired awareness seizures and memory impairment that was mediated by autoimmune nonparaneoplastic LE and comorbid autoimmune disorders (ie, Hashimoto thyroiditis and vitiligo). Neuroimaging studies demonstrated hyperintensities in the medial temporal lobes bilaterally on T2WI MRI sequences. Serial EEGs showed bitemporal intermittent delta activity as well as epileptiform discharges. Tumor blood markers and onconeural antibodies were negative. Immunological screening revealed extremely high GAD-Abs titers in both serum and CSF, as well as the presence of CSF oligoclonal bands. Neuropsychological testing revealed anterograde amnesia with relative preservation of more remote, premorbid memories. The patient underwent first-line immunotherapy followed by immunosuppressive maintenance treatment that led to a reduction of seizures, EEG improvement, and a significant decline in GAD-Abs titers. Neuropsychological evaluations at 5 months, 1 year, and 6 years posttreatment demonstrated improvement, particularly in recent memory and everyday functionality. In this case of anti-GAD LE, the long-term seizure reduction and the improvement of neuropsychological deficits were most likely related to the immunotherapy.

A Preliminary Study of Proinflammatory Cytokines and Depression Following West Nile Virus Infection

West Nile virus (WNV) is a neurotropic flavivirus that can cause acute febrile illness leading to neuroinvasive disease. Depression is a well-described outcome following infection, but the underlying pathogenic mechanisms are unknown. Proinflammatory cytokines play important roles in WNV infection, but their role in depression post-WNV remains unstudied. This research aimed to retrospectively evaluate associations between proinflammatory cytokines and new onset depression in a WNV cohort. Participants with asymptomatic WNV infection were significantly less likely to report new onset depression when compared to those with symptomatic disease. Participants with encephalitis and obesity were significantly more likely to report new onset depression post-infection. Based on univariate analysis of 15 antiviral or proinflammatory cytokines, depression was associated with elevated MCP-1 and decreased TNFα, whereas G-CSF was significantly elevated in those with a history of neuroinvasive WNV. However, no cytokines were statistically significant after adjusting for multiple comparisons using the Bonferroni method. While symptomatic WNV infection, encephalitis, and obesity were associated with new onset depression following infection, the role of proinflammatory cytokines requires additional studies. Further research involving paired acute-convalescent samples, larger sample sizes, and additional data points would provide additional insight into the impact of the inflammatory response on WNV-mediated depression.

Pediatric GAD-65 Autoimmune Encephalitis: Assessing Clinical Characteristics and Response to Therapy With a Novel Assessment Scale

BACKGROUND

Glutamic acid decarboxylase (GAD) encephalitis is a neuroinflammatory disease characterized by a broad range of symptoms including cognitive deficits, behavioral changes, and seizures. Children with this disorder have heterogeneous presentations, and little is known about symptom progression over time and response to immunotherapy.

METHODS

This study reports 10 pediatric GAD encephalitis cases and symptoms found at presentation and follow-up. In addition, symptom severity was reported utilizing a novel scale evaluating functional outcomes across the domains affected by autoimmune encephalitis including cognition, language, seizures, psychiatric symptoms, sleep, and movement. Retrospective chart review was conducted for 10 patients aged <18 years, diagnosed with GAD encephalitis, and followed for one year or more. Chart review included clinical, imaging, and laboratory findings at time of diagnosis and at six- and 12-month follow-ups.

RESULTS

At presentation, cognitive deficits were found in all patients, seizures in six of 10, and language decline in seven of 10. Psychiatric symptoms were prominent for all but one patient with three of nine patients presenting with psychosis. Fatigue, sleep disruption, and movement disorders were less prominent symptoms, occurring in approximately half of the cohort. Cognition and fatigue improved significantly over time when compared with symptom severity, whereas seizures, psychiatric symptoms, and sleep did not. Language and sleep showed improvement only in early stages. Analysis of seizure frequency and type noted variability mirroring trends noted in adult studies of GAD encephalitis.

CONCLUSIONS

This study demonstrated the variability of symptom profiles of pediatric GAD encephalitis and benefits of symptom severity scales. Symptom profiles and progression vary in this population.