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

Dimitrios Adamis; Iulian Coada; Piet Eikelenboom; Che-Sheng Chu; Karen Finn; Vincent Melvin; John Williams; David James Meagher; Geraldine McCarthy

doi:10.5498/wjp.v10.i9.212

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

World J Psychiatry. 2020 Sep 19;10(9):212-222. doi: 10.5498/wjp.v10.i9.212.

Authors

Dimitrios Adamis¹, Iulian Coada¹, Piet Eikelenboom², Che-Sheng Chu³, Karen Finn⁴, Vincent Melvin¹, John Williams⁵, David James Meagher⁶, Geraldine McCarthy¹

Affiliations

¹ Department of Psychiatry, Sligo/Leitrim Mental Health Services, Sligo F91 CD34, Ireland.
² Department of Psychiatry, GGZinGeest and VuMC, Amsterdam 1081 HV, the Netherlands.
³ Department of Psychiatry and Center for Geriatric and Gerontology, Kaohsiung Veterans General Hospital, Kaohsiung 81362, Taiwan.
⁴ Department of Biopharmaceutical and Medical Science, School of Science and Computing, Galway-Mayo Institute of Technology, Galway H91 T8NW, Ireland.
⁵ Department of Pathology, Sligo University Hospital, Sligo F91 H684, Ireland.
⁶ Department of Psychiatry, University Hospital Limerick, Limerick V94 F858, Ireland.

Abstract

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 χ ² = 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 χ ² = 12.231; u: 1, P < 0.001, Wald χ ² = 7.196, u: 1, P = 0.007, Wald χ ² = 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.

Keywords: Cognition; Delirium; Growth hormone; Insulin-like growth factor-I; Old age psychiatry; Older people; Pathophysiology; Physical illness.