Plasma insulin growth factor-1 and incident delirium in older people.

BACKGROUND

A variety of demographic and clinical variables are acknowledged as risk factors for delirium; a syndrome thought to be mediated by abnormalities in a wide range of neurotransmitters. However, little research has been conducted in this field and the role of neuro-immunological factors as a mechanism of medication has received very little attention.

AIMS

To determine if low base line (on admission) IGF-1 levels (a protective cytokine released by brain cells in response to insult) is a risk factor for incident delirium in patients aged 75 and over admitted to an acute medical ward.

METHOD

Base line demographic and clinical variables and serum IGF-1 levels were measured in a consecutive series of 100 non-delirious subjects on inpatient admission. Subjects were assessed daily regarding the development of delirium during the inpatient episode.

RESULTS

Twelve patients developed incident delirium. IGF-1 (OR: 0.822, CI: 0.69, 0.97, p = 0.027), pre-admission cognitive deterioration (assessed by IQCODE) (OR; 3.26, CI: 1.18, 9.04, p = 0.023) and depression (GDS four item: cut-off score > or = 3) (OR; 8.99, CI 1.59,50.76, p = 0.013) were identified as risk factors for developing subsequent delirium.

CONCLUSIONS

Despite the small size of this study our findings suggest that low, pre-morbid IGF-1 is a risk factor for subsequent delirium in this population, emphasizing the potential protective role of this anabolic cytokine and the need for replication of these findings.