Delirium, hallucination, and delusion, is it all confusion?

First of all, no, but confusion exist around these terms concerning their actual meaning and this article aims at clarifying that. Delirium is a common clinical phenomenon and confusional syndrome, often described as a disorder of consciousness. It is characterized by sudden change in a person's mental function, which can disrupt their ability to concentrate, think, remember, and sleep. Impairments in mechanisms that underlie arousal, time perception and attention induce fluctuating consciousness levels, and thereby result in delirium. Medical professionals do not yet fully understand delirium, but it seems to have an association with older age, alcohol withdrawal, and certain medical conditions. Delirium remains a poorly understood and potentially underdiagnosed condition.

Hallucinations are sensory deception that are defined as perception without an adequate external stimulus. Unlike true perceptions, they come from “within”, but individuals experience them as coming from ‘’without’’. Individuals do not always recognize them as not true. Hallucinations are not only associated with psychiatric and organic illness, but it can also occur in healthy individuals. They can be among others visual, auditory, olfactory, gustatory, or hallucinations. One interesting example is functional hallucination, in which individuals simultaneously perceive the hallucination and the real stimuli.

Lastly, delusions are defined as clearly false beliefs that indicate an abnormality of content of thought in an individual. He is concerned that the belief is true regardless of evidence to the contrary, and more often than not, delusions are far away from the evidence. They are not accounted for by the person’s cultural or religious background or level of intelligence. Compared to obsessions and over-valued ideas, delusional ideas are more often culturally or class deviant.