Immunologically mediated dementias

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.

Autoimmune-mediated encephalitis and mimics: A neuroimaging review

Autoimmune encephalitis is a category of autoantibody-mediated neurological disorders that often presents a diagnostic challenge due to its variable clinical and imaging findings. The purpose of this image-based review is to provide an overview of the major subtypes of autoimmune encephalitis and their associated autoantibodies, discuss their characteristic clinical and imaging features, and highlight several disease processes that may mimic imaging findings of autoimmune encephalitis. A literature search on autoimmune encephalitis was performed and publications from neuroradiology, neurology, and nuclear medicine literature were included. Cases from our institutional database that best exemplify major imaging features were presented.

Importance of high-quality evidence regarding the use of Bacopa monnieri in dementia

Background

Bacopa monnieri (BM), a commonly used herb, has shown neuroprotective effects in animal and in vitro studies; but human studies on patients with Alzheimer's Disease (AD) have been inconclusive. Further high-quality trials are required to conclusively state the utility of BM in AD and other neurodegenerative dementias.

Methods

In the present study, we did a narrative review of the current challenges in designing clinical trials of BM in dementia and their evidence-based recommendations.

Results

Many facets of the BM trials need improvement, especially effect size and sample size estimation. Current assessment and outcomes measures need a more holistic approach and newer scales for diagnosing and monitoring prodromal AD. The stringent guidelines in CONSORT and STROBE are often considered difficult to implement for clinical trials in ayurvedic medications like BM. However, adherence to these guidelines will undoubtedly improve the quality of evidence and go a long way in assessing whether BM is efficacious in treating AD/prodromal AD patients and other neurodegenerative dementias.

Conclusion

Future studies on BM should implement more randomized controlled trials (RCTs) with an appropriate sample size of accurately diagnosed AD/prodromal AD patients, administering a recommended dosage of BM and for a pre-specified time calculated to achieve adequate power for the study. Researchers should also develop and validate more sensitive cognitive scales, especially for prodromal AD. BM should be evaluated in accordance with the same rigorous standards as conventional drugs to generate the best quality evidence.

Cognitive, Psychiatric, and Motor Symptoms-Based Algorithmic Approach to Differentiate Among Various Types of Dementia Syndromes

ABSTRACT

It may be difficult to distinguish among the various dementia syndromes due to the overlap in many common clinical features across the dementias. Accurate diagnosis of dementia type is increasingly important in an era when promising disease-modifying agents can be marketed soon. In this review, we outline a clinical algorithmic approach particularly tailored to the major forms of dementia in the clinic and refined from our accumulated experience of these patients. We first present an algorithmic approach for patients presenting with predominant deficits in episodic memory, executive function, language, visuospatial, and apraxia. We then consider types of dementia that mainly cause behavioral and psychiatric changes. Finally, we illustrate clinical pearls regarding motor deficits as key associations of each syndrome.

Successful Treatment of Incomplete Susac Syndrome with Simultaneous Corticosteroids and Plasmapheresis Followed by Rituximab

We present a case report of a patient with incomplete Susac syndrome. He had cognitive impairment, corpus callosum lesions, and vestibulocochlear dysfunction on brainstem auditory evoked responses. He was treated with methylprednisolone and plasmapheresis, improved, and then, also received rituximab. His improvement has been lasting as of this writing. This case shares our experience with a successful treatment of this rare condition that is incompletely understood and lacks well-established treatment guidelines.

Impact of Social Frailty on Alzheimer's Disease Onset: A 53-Month Longitudinal Cohort Study

We investigated the association between social frailty and Alzheimer's disease (AD) incidence among community-dwelling older adults in Japan. A 53-month follow-up cohort study was conducted in Obu City, Japan. Participants comprised 3,720 community-dwelling older adults (mean age, 71.7 years; 48.4% men). The operational definition of social frailty comprised five items: going out infrequently, rarely visiting friends, feeling unhelpful to friends or family, living alone, and not always talking with someone each day. During follow-up, the cumulative AD incidence risk between socially robust, pre-frail, and frail groups was 4.1%, 5.5%, and 10.7%, respectively. In both crude (HR 2.72, 95% CI 1.90-3.89, p < 0.001) and adjusted Cox proportional hazards models (HR 1.53, 95% CI 1.03-2.28, p = 0.035), social frailty was associated with a significantly higher AD incidence risk. The present study revealed that social frailty is strongly associated with AD incidence among Japanese older adults. Further research should elucidate whether social frailty prevention is effective for decreasing AD risk.

Rapidly Progressive Dementia: Prevalence and Causes in a Neurologic Unit of a Tertiary Hospital in Brazil

BACKGROUND

Rapidly progressive dementia (RPD) is usually associated with Creutzfeldt-Jakob disease, a fatal condition. Current advances in the understanding of immune-mediated diseases allow the diagnosis of previously unrecognized treatable RPDs.

OBJECTIVE OF THE STUDY

The objective of the study was to describe the prevalence and causes of RPD in a neurology service, identifying potentially reversible causes.

METHODS

We carried out a cross-sectional evaluation of all patients admitted to the neurology unit of a tertiary hospital in Brazil between March 2012 and February 2015. We included patients who had progressed to moderate or severe dementia within a few months or up to 2 years at the time of hospitalization, and used multivariable logistic regression analysis to identify factors associated with a favorable outcome.

RESULTS

We identified 61 RPD (3.7%) cases among 1648 inpatients. Mean RPD patients' age was 48 years, and median time to progression was 6.4 months. Immune-mediated diseases represented the most commonly observed disease group in this series (45.9% of cases). Creutzfeldt-Jakob disease (11.5%) and nonprion neurodegenerative diseases (8.2%) were less common in this series. Outcome was favorable in 36/61 (59.0%) RPD cases and in 28/31 (89.3%) of immune-mediated cases. Favorable outcome was associated with shorter time from symptom onset to diagnosis and abnormal cerebrospinal fluid findings.

CONCLUSIONS

Immune-mediated diseases were the most common cause of RPD in this series. Timely evaluation and diagnosis along with institution of appropriate therapy are required in RPD, especially in view of potentially reversible causes.

Social Engagement and Its Change are Associated with Dementia Risk among Chinese Older Adults: A Longitudinal Study

This study aimed to examine the association of social engagement (SE) and changes in SE with the risk of dementia among older adults in China. Data were collected from the 2002, 2005, 2008/2009, and 2011/2012 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Random-effects logistic regression models were used to examine the association of SE and changes in SE with the risk of dementia. Of the 7511 older Chinese adults aged 65 years and over, 338 developed dementia during the 9-year follow-up. SE was associated with dementia risk after adjusting for sociodemographic characteristics, lifestyles and health status (odds ratio (OR) = 0.71, 95% confidence interval (CI) = 0.63–0.81). Participants with consistently high or increased SE had a lower risk of dementia than those with consistently low SE ((OR = 0.14, 95% CI = 0.06–0.28 and OR = 0.33, 95% CI = 0.23–0.48, respectively). Higher SE can reduce the risk of dementia. Furthermore, consistently high or increasing SE is associated with a lower risk of dementia.

Autoimmune Encephalitis: Pathophysiology and Imaging Review of an Overlooked Diagnosis

Autoimmune encephalitis is a relatively new category of immune-mediated disease involving the central nervous system that demonstrates a widely variable spectrum of clinical presentations, ranging from the relatively mild or insidious onset of cognitive impairment to more complex forms of encephalopathy with refractory seizure. Due to its diverse clinical features, which can mimic a variety of other pathologic processes, autoimmune encephalitis presents a diagnostic challenge to clinicians. Imaging findings in patients with these disorders can also be quite variable, but recognizing characteristic findings within limbic structures suggestive of autoimmune encephalitis can be a key step in alerting clinicians to the potential diagnosis and ensuring a prompt and appropriate clinical work-up. In this article, we review antibody-mediated encephalitis and its various subtypes with a specific emphasis on the role of neuroimaging in the diagnostic work-up.

History repeating itself: Arnaud's case of pathological déjà vu

We present a translation of Arnaud's (1896) case report of Patient Louis, a case he describes as having a pathological form of déjà vu. Louis has the delusional belief that the present moment is a repetition of an exact same previous event. Arnaud's paper is critical for two reasons. Firstly, it is amongst the first articles in the scientific literature to describe the déjà vu experience using the term 'déjà vu'. Secondly, the case report of someone with delusional and persistent déjà vu, anticipates recently reported cases with similar symptoms, which are beginning to gain interest as a particular form of memory disorder. We offer a contemporary analysis of Louis and conclude that, whilst the article was critical in the development of déjà vu as a scientific concern, Louis's distorted memory is not best described as déjà vu, but rather as a form of reduplicative paramnesia described as recollective confabulation.

The use of cerebrospinal fluid and neuropathologic studies in neuropsychiatry practice and research

The gold standard for diagnosis of neurodegenerative diseases (ie, Alzheimer disease, frontotemporal dementia, Parkinson disease, dementia with Lewy bodies, amyotrophic lateral sclerosis) is neuropathologic examination at autopsy. As such, laboratory studies play a central role in antemortem diagnosis of these conditions and their differentiation from the neuroinflammatory, infectious, toxic, and other nondegenerative etiologies (eg, rapidly progressive dementias) that are encountered in neuropsychiatric practice. This article summarizes the use of cerebrospinal fluid (CSF) laboratory studies in the diagnostic evaluation of dementia syndromes and emerging CSF biomarkers specific for underlying neuropathology in neurodegenerative disease research.

Cell-surface central nervous system autoantibodies: clinical relevance and emerging paradigms

The recent discovery of several potentially pathogenic autoantibodies has helped identify patients with clinically distinctive central nervous system diseases that appear to benefit from immunotherapy. The associated autoantibodies are directed against the extracellular domains of cell-surface-expressed neuronal or glial proteins such as LGI1, N-methyl-D-aspartate receptor, and aquaporin-4. The original descriptions of the associated clinical syndromes were phenotypically well circumscribed. However, as availability of antibody testing has increased, the range of associated patient phenotypes and demographics has expanded. This in turn has led to the recognition of more immunotherapy-responsive syndromes in patients presenting with cognitive and behavioral problems, seizures, movement disorders, psychiatric features, and demyelinating disease. Although antibody detection remains diagnostically important, clinical recognition of these distinctive syndromes should ensure early and appropriate immunotherapy administration. We review the emerging paradigm of cell-surface-directed antibody-mediated neurological diseases, describe how the associated disease spectrums have broadened since the original descriptions, discuss some of the methodological issues regarding techniques for antibody detection and emphasize considerations surrounding immunotherapy administration. As these disorders continue to reach mainstream neurology and even psychiatry, more cell-surface-directed antibodies will be discovered, and their possible relevance to other more common disease presentations should become more clearly defined.

Ethics in prion disease

This paper is intended to discuss some of the scientific and ethical issues that are created by increased research efforts towards earlier diagnosis, as well as to treatment of, human prion diseases (and related dementias), including the resulting consequences for individuals, their families, and society. Most patients with prion disease currently are diagnosed when they are about 2/3 of the way through their disease course (Geschwind et al., 2010a; Paterson et al., 2012b), when the disease has progressed so far that even treatments that stop the disease process would probably have little benefit. Although there are currently no treatments available for prion diseases, we and others have realized that we must diagnose patients earlier and with greater accuracy so that future treatments have hope of success. As approximately 15% of prion diseases have a autosomal dominant genetic etiology, this further adds to the complexity of ethical issues, particularly regarding when to conduct genetic testing, release of genetic results, and when or if to implement experimental therapies. Human prion diseases are both infectious and transmissible; great care is required to balance the needs of the family and individual with both public health needs and strained hospital budgets. It is essential to proactively examine and address the ethical issues involved, as well as to define and in turn provide best standards of care.

Rapidly progressive dementia due to neurosarcoidosis

Rapidly progressive dementia (RPD) is typically defined as a cognitive decline progressing to severe impairment in less than 1-2 years, typically within weeks or months. Accurate and prompt diagnosis is important because many conditions causing RPD are treatable. Neurosarcoidosis is often cited as an unusual reversible cause of RPD.

Diagnosis and evaluation of a patient with rapidly progressive dementia

While the most common dementia is Alzheimer disease (AD), a detailed history is needed to rule out rapidly progressive dementias (RPDs). RPDs are less than two years in duration and have a rate of progression faster typical neurodegenerative diseases. Identification of RPDs is important as some are treatable. This review focuses on the spectrum of RPDs, with special emphasis on paraneoplastic disorders and Creutzfeldt-Jakob disease (CJD).

Diagnosis and treatment of rapidly progressive dementias

Rapidly progressive dementias are conditions that typically cause dementia over weeks or months. They are a particular challenge to neurologists as the differential diagnosis often is different from the more typical, slowly progressive dementias. Early and accurate diagnosis is essential, as many of the etiologies are treatable. The information in this review is in part based on experience through our rapidly progressive dementia program at the University of California San Francisco, Memory and Aging Center. As treatment of a rapidly progressive dementia is entirely dependent on the diagnosis, we present a comprehensive, structured, but pragmatic approach to diagnosis, including key clinical, laboratory, and radiologic features. For the 2 most common causes of rapid dementia, treatment algorithms for the autoimmune encephalopathies and symptomatic management for the neurodegenerative causes are discussed.