P/Q-Type Calcium Channel Antibodies and Late Life First Break Psychosis: A Case Report

Abstract

<h3>Introduction</h3> Paraneoplastic Syndrome, described in the 1940s, a phenomenon of cancer presenting with multiple different manifestations, not directly related to tumor itself, has had an overdue recognition with these conditions still being studied and researched, especially when it comes to Paraneoplastic Syndromes presenting with Neuropsychiatric Disorders (Lorraine C. Pelosof, 2010). In the psychiatric and neurological literature, there is slow yet gradual recognition of new onset psychosis in patients with no prior history of such, which are attributable to autoantibodies of different types. In some psychiatric literature, this presentation is termed as autoimmune psychosis (Thomas A Pollak, 2020). Currently known autoantigens include NMDAR, Gamma-Aminobutyric Acid Receptor- B (GABABR), Gamma-Aminobutyric Acid Receptor- A (GABAAR), components of voltage gated potassium channel (VGKC) complex, dopamine D2 receptor (D2R)(Nese Sinmaz, 2015). Autoimmune N-methyl-D-aspartate (NMDA) receptor encephalitis has been of particular interest to psychiatrists with it being the most studied paraneoplastic syndrome, as 77% of affected patients first present to psychiatry with a broad range of symptoms (Jennifer L.Kruse, 2015). Very few and limited data have been found on the association between voltage gated calcium channel (P/Q type) and psychosis. In this poster, we describe a case of an individual presenting with late onset first episode of psychosis, with positive P/Q channel antibodies. <h3>Methods</h3> Previous studies and reviews over the past 10 years were reviewed using PubMed, Medline and Google Scholar. Search terms were "psychosis", "autoimmune psychosis", "autoantibodies and psychosis" "geriatric psychosis" "P/Q-type Calcium channel" "Paraneoplastic syndrome" "very late onset psychosis". We reviewed available literature with regards to first episode of psychosis in old age and possible association with P/Q-type voltage gated calcium channel. <h3>Results</h3> DiscussionVery late onset psychosis is delineated as onset of psychosis after the age of 60 years (Howard, 2000). Prevalence of late life psychosis is 23%, however 60% of new onset psychosis in older individuals are of secondary etiology (Cohen, 2015). Psychosis in the elderly individuals could be primarily due to Very Late Onset Schizophrenia Like Psychosis (VLOSLP) vs secondary causes (Delirium, Dementia, Drugs/illicit substances/toxin, Medical conditions). In the discussed case, the patient presented with first episode of psychosis at the age of 70. The extensive workup was positive for P/Q-type Calcium channel binding antibody. Per literature review, the positive predictive value for an autoimmune neurological diagnosis (Lambert-Eaton syndrome or diverse encephalomyeloneuropathic phenotypes) among patients with positive values for P/Q -type calcium channel antibodies < 0.10 nM is 19%. The positive predictive value for a cancer diagnosis (diverse types) among patients positive for P/Q-type calcium channel antibody is 21%; approximately 18% are historical neoplasms, and 3% are detected prospectively (Zalewski NL, 2016). A spectrum of psychiatric autoimmunity beyond NMDA-R IgG is still under-recognized (Jennifer L.Kruse, 2015). In a retrospective case control study conducted by Dr. Jennifer L.Kruse in Mayo clinic, out of the 213 adult psychiatric inpatient 3 patients were found to have positive P/Q-type Calcium channel, who manifested with delusional parasitosis, mood disorder with psychotic features, and Major Depressive Disorder with Psychotic features (Jennifer L.Kruse, 2015). Another international case study found genetic association between voltage gated Calcium channel and Schizophrenia (Wen Li1, 2018). While these studies indicate the potential association between voltage gated Calcium channel and psychosis, limited case studies and research could be found on the association, extent and elaboration of the aforementioned. <h3>Conclusions</h3> While there is progressively enriched literature on psychosis due to Paraneoplastic syndrome, specifically Anti NMDA receptor encephalitis, there is not much mention of correlation between P/Q-type calcium channel binding antibodies and psychosis. Cases with rare presentations as above warrant elaborate workup. Along with the abovementioned etiologies, given the increased incidence of psychosis due to autoimmune antibodies, addition of full autoimmune antibody panel should be considered. Shared clinical experience, research and prospective clinical studies will direct developing guidelines for evaluation, management and prognostic indicators of Paraneoplastic Syndromes with Neuropsychiatric symptoms, particularly due to autoimmunity against voltage gated calcium channel (P/Q-type). <h3>This research was funded by</h3> There are no financial conflicts of interest to disclose