Delusional experiences and neurobiology : Karl Jasper remembered. Schiz Bulletin. March.2013


Karl Jaspers (1883–1969) has made tremendous contributions in building the scientific foundations of psychiatry. On the centenary year of the publication of Jaspers’ General Psychopathology (Allgemeine Psychopathologie , 1913) his contributions are reviewed in this article.

Jasper proposed three crucial criteria for delusions: subjective certainty, imperviousness to counter arguments and implausibility of content. These criteria are external, ie what we make of the reported ideas.  This do not consider the more crucial one; the central subjective experience crucial to the primary delusion, because what ever the patient tell us is a report mediated by memory and editing.

Jasper described that delusions in alcoholics ( eg: jealousy) are slow to develop and the whole occurrence may be understood as a change or development of personality ( ie understandable) . In contrast to this the process in schizophrenia is an irreversible, inexplicable, suddenly emergent change. “Something entirely new enters without any connection to what was before”. This threatens the continuity of self/ personality.In Jasper’s view, these delusions cannot be derived from some prior experience, motivation, or inner psychological connectedness in the patient.

When Clinician attempts to explore these delusions, the empathic understanding falters and she/he experiences the limits of this understanding. The clinician thus concludes that these delusions are non nonunderstandable in terms of the person’s history/culture/motivation etc. The delusion creates a new world for the deluded person.

These ideas are illuminated by symptoms reported in the prodrome phase of schizophrenia. Delusional mood is the first subjective phenomenological experience of something radically new, or alien, entering in prodromal psychosis. Patients feel that there is something suspicious around.. a delusional atmosphere is vague but disturbing… At the beginning of process disorders, no clear definite meaning accompanies these perceptions… .The delusional mood experiences by prodromal subjects have been reinterpreted recently as Truman symptoms ( Truman show- movie).

How do biology explain delusional mood and experience?

Kapur suggests that dopamine mediates the “salience” of environmental events and their mental representations.There are numerous stimuli entering our mind from outside. One has to be selective in attention. Stimuli will be prioritized according to their “saliency”/relevance. Their features are compared with their context. Stimulus-driven processing interacts with internal factors ( goals, beliefs, and history) to determine the salience. What come next is the goal directed behavior. This is influenced by reward and avoidance of punishment. It is well established that dopamine play a crucial role in this. Dopaminergic neurotransmission is essential for signaling reward and salience. Abnormal striatal dopamine firing in early psychosis could  lead to the aberrant assignment of salience to neutral stimuli  and therefore underlie the emergent delusional mood and Truman-like symptoms. Primary delusions may arise from the prodromal state as the individual’s own explanation of the experience of aberrant salience.

Jasper’s ideas about the nature of primary delusions and the process involved in its formation  has generated  neurobiological  models. The idea that delusion is formed through loss of context in its experiential origins and memory is a product of such thinking. 100 years have passed, still Jaspers descriptions and ideas remain influential in how we try to understand the delusional experiences.

Summary of the article:

The phenomenology and neurobiology of delusion formation during psychosis onsetjasperstruman symptoms, and aberrantsalience.

Mishara AL, Fusar-Poli P. Schizophr Bull. 2013 Mar;39(2):278-86.

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