Phenomenological, subjective experience and neurobiological aspects of delirium

After briefly considering the main clinical manifestations of delirium, the authors concentrate on some aspects of the experience that is indeed lived during the course of this disorder. The opportunity to understand such experience would appear unlikely, although some debate subsists. The only source of information on the topic seems to be the a posteriori report provided by the patient, which inevitably includes the effects of a distorted recollection of the experience actually lived during delirium. However, such an experience would appear especially interesting and worth analyzing due to the deep psychological and ethological meaning that the contents of the hallucinatory and delusional symptoms seem to have. With regards to the neurobiological aspects involved in delirium, it seems that a decrease in central cholinergic activity causes a disturbance of consciousness, whereas an increase in dopaminergic activity appears to be responsible for the clinical manifestations of “hyperactivity” (hallucinations, delusions, insomnia, psychomotor agitation etc...) observed during the disorder. Lastly, the results of recent studies on the pathophysiology of delirium have led to new perspectives which appear to be especially promising from both the heuristic and therapeutic points of view. In fact, it seems that changes in the levels of some cytokines are involved in the pathophysiology of the disorder and that some endogenous substances, such as insulin growth factor 1 (IGF-1) and somatostatin play a neuroprotective role and likely possess therapeutic properties in treating delirium.