A long-term follow-up study of cerebrospinal fluid somatostatin in delirium

Delirium, insulin-like growth factor I, growth hormone in older inpatients

BACKGROUND

Delirium is a common disorder in elderly medical inpatients with serious adverse outcomes and is characterized by sudden onset, disturbance in attention, awareness, consciousness and cognition, and often with behavioural disturbances. Central to understanding delirium, is understanding mechanisms by which body and brain wellbeing are linked and in particular how brain responses to bodily homeostatic stress is mediated. A number of studies have investigated the relationship between insulin-like growth factor I (IGF-I) and delirium in medically ill hospitalised patients with conflicting results. However, none have investigated growth hormone (GH) which is related to IGF-I via negative feedback.

AIM

To investigate the relationship between serum levels of IGF-I and GH, and the occurrence of delirium.

METHODS

Prospective, longitudinal, observational study. Consecutive elderly inpatients (aged 70+), were assessed twice weekly with Montreal cognitive assessment (MoCA), Confusion assessment method (CAM), Acute Physiology and Chronic Health Evaluation II. Delirium was defined using CAM. Previous history of dementia was evaluated with the Informant Questionnaire on Cognitive Decline in the Elderly. IGF-I and GH levels were estimated with the ELISA method. Generalized estimating equations (GEE) model was applied for the first five assessments to analyze those longitudinal data.

RESULTS

The sample consisted of 198 participants (mean age 80.63 ± 6.81; range 70-97). Of these 92 (46.5%) were females. Eighty six (43.4%) were identified with a history of dementia. Incident or prevalent delirium during hospitalisation was identified with CAM in 40 participants (20.2%). Evaluation of missing values with Little's MCAR test indicated that they were missing completely at random (MCAR χ² = 12.24, u: 9, P = 0.20). Using GEE for the analysis we found that low MoCA scores, low levels of IGF-I and high levels of GH were significantly associated with any delirium (prevalence, incident, or fluctuating , during the study period (Wald χ² = 12.231; u: 1, P < 0.001, Wald χ² = 7.196, u: 1, P = 0.007, Wald χ² = 6.210; : u: 1, P = 0.013 respectively).

CONCLUSION

The results show that low levels of IGF-I, high levels of GH and low scores in cognition are independently associated with the occurrence of any delirium during the hospitalisation of medically ill older people. The results of the study supports the hypothesis that deficits in the immunoreactivity of the brain (low cerebral reserve) may be associated with delirium.

CSF biomarkers in delirium: a systematic review

OBJECTIVE

In recent years, there has been a blossoming of studies examining cerebrospinal fluid (CSF) as a method of studying the pathophysiology of delirium. We systematically reviewed the literature for CSF studies in delirium and provide here a summary of the implications for our understanding of delirium pathophysiology. We also summarise the methods used for CSF analysis and discuss challenges and implications for future studies.

METHODS

In this systematic review, we screened MEDLINE, EMBASE, PsycINFO, Web of Science, PubMed and the Cochrane Library for articles on CSF biomarkers in delirium, published on 3 September 2016. Studies were required to use Diagnostic and Statistical Manual of Mental Disorders or International Classification of Diseases criteria for delirium or a validated tool. We excluded case reports. There were no other restrictions on study type.

RESULTS

We identified 3280 articles from our initial search, and 22 articles were included in this review. All studies were prospective, including over 400 patients with delirium and 700 controls. More than 70 different biomarkers were studied. Studies could not be compared with each other for meta-analysis because of their heterogeneity and varied widely in their risk of bias and quality assessments.

CONCLUSIONS

The 22 studies identified in this review reveal a small but growing literature, in which many of the important hypotheses in delirium pathogenesis have been examined, but from which few firm conclusions can currently be drawn. Nevertheless, the overall interpretation of the literature supports the vulnerable brain concept, that is, that biomarker evidence of, for example, Alzheimer's disease pathology and/or neuroinflammation, is associated with delirium.

A systematic literature review of cerebrospinal fluid biomarkers in delirium

BACKGROUND

Cerebrospinal fluid (CSF) analysis has great potential to advance understanding of delirium pathophysiology.

METHODS

A systematic literature review of CSF studies of DSM or ICD delirium was performed.

RESULTS

In 8 studies of 235 patients, delirium was associated with: elevated serotonin metabolites, interleukin-8, cortisol, lactate and protein, and reduced somatostatin, β-endorphin and neuron-specific enolase. Elevated acetylcholinesterase predicted poor outcome after delirium and higher dopamine metabolites were associated with psychotic features.

CONCLUSIONS

No clear conclusions emerged, but the current literature suggests multiple areas for further investigation with more detailed studies.

Insulin-like growth factor I and the pathogenesis of delirium: a review of current evidence

Delirium is a frequent complication in medically ill elderly patients that is associated with serious adverse outcomes including increased mortality. Delirium risk is linked to older age, dementia, and illness that involves activation of inflammatory responses. IGF-I is increasingly postulated as a key link between environmental influences on body metabolism with a range of neuronal activities and has been described as the master regulator of the connection between brain and bodily well-being. The relationships between IGF-I and ageing, cognitive impairment and inflammatory illness further support a possible role in delirium pathogenesis. Five studies of IGF-I in delirium were identified by a systematic review. These conflicting findings, with three of the five studies indicating an association between IGF-1 and delirium occurrence, may relate to the considerable methodological differences in these studies. The relevance of IGF-I and related factors to delirium pathogenesis can be clarified by future studies which account for these issues and other confounding factors. Such work can inform therapeutic trials of IGF-I and/or growth hormone administration.

Pathoetiological model of delirium: a comprehensive understanding of the neurobiology of delirium and an evidence-based approach to prevention and treatment

Delirium is the most common complication found in the general hospital setting. Yet, we know relatively little about its actual pathophysiology. This article contains a summary of what we know to date and how different proposed intrinsic and external factors may work together or by themselves to elicit the cascade of neurochemical events that leads to the development delirium. Given how devastating delirium can be, it is imperative that we better understand the causes and underlying pathophysiology. Elaborating a pathoetiology-based cohesive model to better grasp the basic mechanisms that mediate this syndrome will serve clinicians well in aspiring to find ways to correct these cascades, instituting rational treatment modalities, and developing effective preventive techniques.

Clinical pharmacology of old age syndromes

Several syndromes occur in old age. They are often associated with increased mortality and in all there is a paucity of basic and clinical research. The recent developments in the clinical pharmacology of three common syndromes of old age (delirium, urinary incontinence, and falls) are discussed along with directions for future research.

Entry criteria and baseline characteristics predict outcome in acute stroke trials

Background and Purpose-We sought to study the range of entry criteria and baseline characteristics in acute stroke trials and to understand their effects on patient outcomes.

METHODS

-Randomized, placebo-controlled therapeutic trials in patients with acute ischemic stroke were identified. Entry criteria, baseline clinical characteristics, and outcome were extracted for the placebo group of each trial. The relationship between key variables was then determined.

RESULTS

-Across 90 placebo groups identified, there was great variation in entry criteria and outcome measures. This was associated with divergent outcomes; for example, in some studies most placebo group patients died, while in other studies nearly all had no disability. Entry criteria were significantly correlated with outcome; for example, higher age cutoff for study entry correlated with 3-month mortality. Entry criteria also predicted baseline clinical characteristics; for example, wider time window for study entry correlated directly with time to treatment and inversely with stroke severity (initial National Institutes of Health Stroke Scale score). Baseline characteristics predicted outcome. Greater stroke severity predicted higher 3-month mortality rate; despite this, successful thrombolytic trials have enrolled more severe strokes than most trials. The mean age of enrollees also predicted 3-month mortality and was inversely related to percentage of patients with 3-month Barthel Index score >/=95. The strongest predictors of 3-month mortality were obtained with multivariate models.

CONCLUSIONS

-Acute stroke studies vary widely in entry criteria and outcome measures. Across multiple studies, differences in entry criteria, and the baseline clinical characteristics they predict, influence patient outcomes along a continuum. In some studies, enrolling a specific subset of patients may have improved the chances of identifying a treatment-related effect, while in others, such chances may have been reduced. These findings may be useful in the design of future stroke therapeutic trials.

Etiologic and outcome profiles in hypoactive and hyperactive subtypes of delirium

The existence of hyperactive, hypoactive, or mixed clinical subtypes of delirium is widely accepted. But relationships between these motor profiles and etiology or outcome remain unclear. The aim of this study was to compare etiologic and outcome profiles in a case series of 183 elderly patients (mean age = 84.1 years, SD = 5.9) consecutively admitted into the geriatric wards of two French university hospitals or referred to a geriatric psychiatry consultation-liaison unit within a Swiss university hospital. All patients met DSM-III-R criteria for delirium and were classified into clinical subtypes according to the results of a previous factor analysis of scores on a 19-item checklist rating a wide range of delirium symptoms. The hyperactive subtype was more frequent (n = 85, 46.5%) than the unspecified (n = 50, 27.3%) and hypoactive subtypes (n = 48, 26.2%). There was no significant difference in terms of etiologic or outcome profile between clinical subtype groups. The presence of acute metabolic disorders, cardiovascular disease, and hyperthermia as etiologic factors was significantly associated with full recovery of the episode at 3 weeks follow-up, whereas probable preexisting dementia was significantly associated with partial recovery or failure to recover.

Delirium phenomenology illuminates pathophysiology, management, and course

The phenomenology of delirium has received little standardized longitudinal study but offers the prospect of valuable insights regarding clinical subtypes, differentiation from other neuropsychiatric disorders, identification of underlying pathophysiologies, management, and course. This review examines current approaches to the investigation of delirium phenomenology and how the findings to date illuminate our understanding of delirium. It concludes with recommendations for future investigations.