Delirium in Parkinson's Disease: A Cocktail Diagnosis

Interleukin-6 mediates delirium-like phenotypes in a murine model of urinary tract infection

Background

Urinary tract infection (UTI) is frequently implicated as a precipitant of delirium, which refers to an acute confusional state that is associated with high mortality, increased length of stay, and long-term cognitive decline. The pathogenesis of delirium is thought to involve cytokine-mediated neuronal dysfunction of the frontal cortex and hippocampus. We hypothesized that systemic IL-6 inhibition would mitigate delirium-like phenotypes in a mouse model of UTI.

Methods

C57/BL6 mice were randomized to either: (1) non-UTI control, (2) UTI, and (3) UTI + anti-IL-6 antibody. UTI was induced by transurethral inoculation of 1 × 10⁸Escherichia coli. Frontal cortex and hippocampus-mediated behaviors were evaluated using functional testing and corresponding structural changes were evaluated via quantification of neuronal cleaved caspase-3 (CC3) by immunohistochemistry and western blot. IL-6 in the brain and plasma were evaluated using immunohistochemistry, ELISA, and RT-PCR.

Results

Compared to non-UTI control mice, mice with UTI demonstrated significantly greater impairments in frontal and hippocampus-mediated behaviors, specifically increased thigmotaxis in Open Field (p < 0.05) and reduced spontaneous alternations in Y-maze (p < 0.01), while treatment of UTI mice with systemic anti-IL-6 fully reversed these functional impairments. These behavioral impairments correlated with frontal and hippocampal neuronal CC3 changes, with significantly increased frontal and hippocampal CC3 in UTI mice compared to non-UTI controls (p < 0.0001), and full reversal of UTI-induced CC3 neuronal changes following treatment with systemic anti-IL-6 antibody (p < 0.0001). Plasma IL-6 was significantly elevated in UTI mice compared to non-UTI controls (p < 0.01) and there were positive and significant correlations between plasma IL-6 and frontal CC3 (r² = 0.5087/p = 0.0028) and frontal IL-6 and CC3 (r² = 0.2653, p < 0.0001).

Conclusions

These data provide evidence for a role for IL-6 in mediating delirium-like phenotypes in a mouse model of UTI. These findings provide pre-clinical justification for clinical investigations of IL-6 inhibitors to treat UTI-induced delirium.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02304-x.

Delirium Research in India: A Systematic Review

Delirium is the most common psychiatric diagnoses encountered in patients with various medical-surgical illnesses, in all the treatment set-ups, with relatively higher incidence and prevalence in the intensive care units. As delirium is encountered in multiple specialties, it is important to understand the research on this diagnosis. This study aims to assess the research output involving patients of delirium from India. A comprehensive search was undertaken using Medline (PubMed) and other databases. Search words included were “delirium,” “delirious,” “delirium tremens” AND “India.” No filters were used. Internet and hand searches yielded 305 articles. Out of these articles, 151 had the terms “delirium,” “delirious,” “delirium tremens” in the title and these were included for the review. Additionally, 14 articles were included for the review, although these did not have these terms in the title, but delirium was one of the major outcome parameters in these studies. Majority of the papers were original articles ( n = 81), and these were followed by, case reports ( n = 58), review articles ( n = 10), letter to the editor (not as case reports but as a communication; n = 13), editorials ( n = 2) and one clinical practice guideline. Most of the original papers have either focused on epidemiology (incidence, prevalence, outcome, etc.), symptom profile, with occasional studies focusing on effectiveness of various pharmacological interventions. There is a dearth of research in the field of delirium from India. There is a lack of studies on biomarkers, evaluation of nonpharmacological interventions, and evaluation of prevention strategies. It is the need of the hour to carry out more studies to further our understanding of delirium in the Indian context.

Parkinson's Disease in Intensive Care Unit: An Observational Study of Frequencies, Causes, and Outcomes

Objective:

To analyze the frequency, causes, and outcomes of admission to the Intensive Care Unit (ICU) among Parkinson's disease (PD) population so that preventive measures can be developed.

Methods:

We prospectively observed patients with diagnosis of PD admitted to ICU from January 2014 to December 2016. Based on etiology for hospital admission, they were divided into two groups – related to PD (further divided into direct or indirect) or not associated with PD at all. Etiology for hospitalization was determined from history and investigational data. The primary outcome was death or discharge from the hospital. Factors contributing to ICU admission were analyzed by comparing these patients with a cohort of 50 PD patients admitted to the neurology ward during the same study period. All values were expressed as mean (standard deviation) and percentages using SPSS version 16.0.

Results:

Fifty-three (36%) out of a total of 146 patients required ICU admission. Most common causes leading to admission in decreasing order of frequency were fever (34%), delirium (16%), falls (12%), encephalopathy (8%), gastrointestinal emergencies (6%); while direct disease-related severe dyskinesias were seen only in two patients (4%). 13.7% needed mechanical ventilation and mean duration of ventilation was 5.94 days with mortality rate of 20%. Significant factors predicting ICU admission, and thus, poor outcomes were age >65 years, history of previous admission within the last 12 months, delirium, and hypoalbuminemia. There was no significant association between the incidence of ICU admission and duration of disease or severity of the disease.

Conclusions:

Poor outcome in PD patients is due to systemic causes, hence multidisciplinary teamwork may improve outcome in these patients.