Association between leptin and delirium in elderly inpatients

The Association of Plasma Leptin, Soluble Leptin Receptor and Total and High-Molecular Weight Adiponectin With the Risk of Perioperative Neurocognitive Disorders

BACKGROUND

Perioperative neurocognitive disorders (NCD) are poorly characterized in terms of their risk factor profiles. Leptin and adiponectin are adipose-tissue-derived hormones with a role in inflammation and atherosclerosis whose function in perioperative NCD is unclear. Here, we used a cohort of older adults to examine the association of preoperative plasma concentrations of these biomarkers with the risk of perioperative NCD.

METHODS

Prospective analysis of 768 participants aged ≥ 65 years of the BioCog study. Blood was collected before surgery for measurement of plasma total and high-molecular-weight (hmw) adiponectin, leptin, and soluble leptin receptor (sOB-R). The free leptin index (FLI, leptin:sOB-R) was calculated. Postoperative delirium (POD) was assessed twice daily until postoperative day 7/discharge. Five hundred twenty-six patients (68.5%) returned for 3-month follow-up and provided data on postoperative cognitive dysfunction (POCD). POCD was defined as a decline on six neuropsychological tests that exceeded that of a nonsurgical control group. Logistic regression analyses examined the associations of each exposure with POD and POCD risk, in separate models adjusted for age, sex, fasting, surgery type, and body mass index (BMI).

RESULTS

Of 768 patients, 152 (19.8%) developed POD. Of 526 attendants of the follow-up, 54 (10.3%) had developed POCD. Leptin, sOB-R, and total and hmw adiponectin were each not associated with POD. For POCD, we observed reduced risk in patients in FLI quartile 4 compared with quartile 1 (odds ratio, 0.26; 95% CI 0.08, 0.89). Sensitivity analyses for the outcome POD revealed statistically significant interaction terms of sOB-R and total adiponectin with obesity (BMI≥30kg/m2 versus BMI<30kg/m2). For the outcome POCD, a higher sOB-R was associated with an increased risk in the obese subgroup (odds ratio, 4.00; 95% CI 1.01, 15.86).

CONCLUSIONS

We did not find consistent evidence for the role of leptin, its receptor, and total and hmw adiponectin in POD and POCD risk. Future research should be used to support or refute our findings and to fully characterize any differences in the associations of these hormones with POD/POCD between obese and nonobese individuals.

Delirium in hospitalized older adults

Delirium is a common and underdiagnosed problem in hospitalized older adults. It is associated with an increased risk of poor cognitive and functional outcomes, institutionalization, and death. Timely diagnosis of delirium and non-pharmacological prevention and management strategies can improve patient outcomes. The Confusion Assessment Method (CAM) is the most widely used clinical assessment tool for the diagnosis of delirium. Multiple variations of the CAM have been developed for ease of administration and for the unique needs of specific patient populations, including the 3-min diagnostic CAM (3D CAM), CAM-Intensive Care Unit (CAM-ICU), Delirium Triage Screen (DTS)/Brief CAM (b-CAM), 4AT tool, and ultrabrief delirium assessment. Strong evidence supports the effectiveness of nonpharmacologic strategies as the primary intervention for the prevention of delirium. Multicomponent delirium prevention strategies can reduce the incidence of delirium by 40%. Investigation of underlying medical precipitants and optimization of non-pharmacological interventions are first line in the management of delirium. Despite a lack of evidence supporting use of antipsychotics, low dose antipsychotics remain second line for off-label treatment of distressing psychoses and/or agitated behaviors that are refractory to non-pharmacological behavioral interventions and pose an imminent risk of harm to self or others. Any antipsychotic prescription for delirium should be accompanied by an appropriate taper plan. Follow up with primary care providers on discharge from hospital for ongoing screening of cognitive impairment is important.

Renal function and delirium in older fracture patients: different information from different formulas?

OBJECTIVES

the association between renal function and delirium has not been investigated in older fracture patients. Creatinine is frequently low in these subjects, which may influence the association between delirium and renal function as estimated with creatinine-based formulas. Cystatin C could be a more reliable filtration marker in these patients.

AIM

to confirm the association between renal function and delirium in older fracture patients comparing creatinine- and cystatin-based estimated glomerular filtration rate (eGFR) METHODS: patients aged 65+ requiring surgery for traumatic bone fractures were included. Six equations were used to calculate eGFR, based on serum creatinine and/or cystatin C obtained within 24 h of admission: Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology (CKD-EPI_cr, CKD-EPI_cys, CKD-EPI_cr-cys) and Berlin Initiative Study equations (BIS-1, BIS-2). Delirium was identified with a chart-based method.

RESULTS

571 patients (mean age 83) were enrolled. Delirium occurred in the 34% and was associated with a lower eGFR regardless of the equation used. In a multivariable model, the association between moderate renal impairment (eGFR 30-60 ml/min/1.73 m²) and delirium remained significant in patients aged 75-84 and only when estimated with cystatin-based or BIS-1 equations. Only dementia was significantly associated with delirium in subjects 85+.

CONCLUSIONS

in older fracture patients, moderate renal impairment was independently associated with delirium only among subjects aged 75-84, when eGFR was estimated with cystatin-based or BIS 1 equations, and not with the most commonly used equations (MDRD, CKD-EPI_cr).

Serum biomarkers of delirium in the elderly: a narrative review

Delirium after surgery and in the intensive care unit (ICU) remains a challenge for patients, families, and caregivers. Over the years, many promising biomarkers have been investigated as potential instruments for risk stratification of delirium. This review aimed to identify and assess the clinical usefulness of candidate serum biomarkers associated with hospital delirium in patients aged 60 years and older. We performed a time-unlimited review of publications indexed in PubMed, Cochrane, Embase, and MEDLINE databases until June 2019 that evaluated baseline and/or longitudinal biomarker measurements in patients suffering from delirium at some point during their hospital stay. A total of 32 studies were included in this review reporting information on 7610 patients. Of these 32 studies, twenty-four studies reported data from surgical patients including four studies in ICU cohorts, five studies reported data from medical patients (1026 patients), and three studies reported data from a mixed cohort (1086 patients), including one study in an ICU cohort. Findings confirm restricted clinical usefulness to predict or diagnose delirium due to limited evidence on which biomarkers can be used and limited availability due to non-routine use.

α-lipoic acid attenuates spatial learning and memory impairment induced by hepatectomy

The aim of the present study was to compare the effects of α-lipoic acid (ALA) on postoperative cognitive dysfunction (POCD) between wild type (WT) and leptin receptor-deficient (db/db) mice and to elucidate the underlying mechanism of treatment with ALA. The present study compared the effects of ALA on spatial learning and memory of WT and db/db mice using a Morris water maze following hepatectomy. The expression levels of proteins, including cyclin-dependent kinase 5 (Cdk5), tau, phosphorylated tau and amyloid β (Aβ) were measured in the hippocampus. Surgery impaired postoperative cognitive function in both WT and db/db mice. Furthermore, the expression levels of Cdk5 and Aβ, and the phosphorylation of tau in the hippocampus increased after the surgery in both WT and db/db mice. The ultrastructure of hippocampal neurons and synapses was analyzed by transmission electron microscopy and the results revealed that surgery damaged the structure of neurons and synapses in both WT and db/db mice. Treatment with ALA protected the postoperative cognitive function and the structure of hippocampal neurons and synapses, and prevented the increase in protein expression levels of Cdk5 and Aβ, and the phosphorylation of tau in the hippocampus of WT but not db/db mice. The results of the present study suggest that ALA may be used for the treatment of POCD. The molecular mechanisms underlying the activity of ALA require further investigation.

Low plasma leptin level at admission predicts delirium in critically ill patients: A prospective cohort study

The pathophysiology of delirium remains poorly understood. Low leptin level has been associated with features leading to delirium such as dysregulated immune functions and loss of neuroprotective effects. The purpose of the present study was to investigate the relationship between plasma leptin level at intensive care unit (ICU) entry and subsequent occurrence of delirium in critically ill patients. This single-center prospective cohort study in China allocated 336 critically ill patients admitted to ICU between 05/2015 and 05/2016 into a delirium group (n=102) and non-delirium group (n=234) based on whether delirium occurred during their stay at the ICU. Patients were examined at least twice daily and delirium was diagnosed using the Confusion Assessment Method for the ICU (CAM-ICU). Blood samples were obtained after ICU entry. Plasma leptin concentrations were measured by ELISA. Delirium occurred in 30.4% (102/336) of patients. Patients who developed delirium showed significantly lower leptin level at ICU entry than those who did not (6.1±3.2 vs. 9.2±5.9ng/mL; P<0.001). Low plasma leptin level at ICU entry was independently associated with subsequent occurrence of delirium (OR, 0.865; 95%CI, 0.802-0.934; P<0.001). Other independent risk factors for delirium included increasing age (OR, 1.050; 95%CI, 1.020-1.080; P=0.001) and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score (OR, 1.148; 95%CI, 1.092-1.208; P<0.001). Patients who developed delirium had a prolonged duration of ICU stay and higher mortality. Low plasma leptin level at ICU entry was associated with the occurrence of delirium in critically ill patients.

Preoperative plasma leptin levels predict delirium in elderly patients after hip fracture surgery

Leptin is considered to be a modulator of the immune response. Hypoleptinemia increases the risk for Alzheimer's disease and vascular dementia. The present study aimed to investigate the ability of plasma leptin level to predict delirium in elderly patients after hip fracture surgery. Postoperative delirium (pod) was evaluated using the Confusion Assessment Method. Prolonged postoperative delirium (ppod) was defined as delirium lasting more than 4 weeks. Plasma leptin levels of 186 elderly patients and 186 elderly controls were measured by an enzyme-linked immunosorbent assay. Plasma leptin level was substantially lower in patients than in controls (4.6±2.2ng/ml vs. 7.5±1.8ng/ml, P<0.001). It was identified as an independent predictor for pod [odds ratio, 0.385; 95% confidence interval (CI), 0.286-0.517; P<0.001] and ppod (odds ratio, 0.283; 95% CI, 0.152-0.527; P<0.001) using a multivariate analysis, and had high area under receiver operating characteristic curve for pod [area under curve (AUC), 0.850; 95% CI, 0.790-0.898] and ppod (AUC, 0.890; 95% CI, 0.836-0.931). The predictive value of leptin was markedly bigger than that of age for pod (AUC, 0.705; 95% CI, 0.634-0.770; P=0.002) and ppod (AUC, 0.713; 95% CI, 0.642-0.777; P=0.019). In a combined logistic-regression model, leptin improved the AUC of age to 0.890 (95% CI, 0.836-0.931) (P<0.001) for pod and 0.910 (95% CI, 0.860-0.947) (P=0.005) for ppod. Thus, preoperative plasma leptin level may be a useful, complementary tool to predict delirium and also prolonged delirium in elderly patients after hip fracture surgery.