Phenomenal insights: Is the idea of defining a delusion overvalued?

Although classification systems such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) define phenomena such as delusions and overvalued ideas (OVI) as distinct, distinguishing them clinically can be difficult. Diagnostic boundaries and severity cut-offs often seem arbitrary and are unable to capture the complexity of such sophisticated psychopathology. A lack of clarity and specificity in conceptualisation creates diagnostic confusion that can misdirect treatment. In practice, ambiguities concerning terminology allow phenomenology to be shaped to accord with pre-existing clinical impressions and diagnostic suppositions, rather than serving to inform them (Walker, 1991). Therefore, this Phenomenal Insight provides a brief introduction to the putative phenomenological distinctions between these terms by evaluating their various conceptualisations.

Delusions

Karl Jaspers (1883–1969), a German psychiatrist and philosopher, has been significantly influential in this area of study. In General Psychopathology (first published in 1913), Jaspers described the delusion proper and the delusion-like idea; concepts that continue to form the basis of our current definitions. He described delusions proper as ‘psychologically irreducible’; a belief held with strong conviction, impervious to experience or counter-argument, and characterised by impossible or bizarre content (Jaspers, 1963). They are, by their very nature, ununderstandable (unverständlich) and direct (unmediated or unmittelbar), in contrast to delusion-like ideas, which are reflective and interpretive (Walker, 1991). In other words, in a delusion proper, the new meaning is implicit in the experience, just as the meaning of ‘to inhabit’ is implicit in the perception of house. Walker (1991) noted that a delusion proper is neither a belief nor a judgement, but rather an experience. For the individual, this results in a new way of seeing the world, without contextual precedent. Jaspers recorded examples of primary delusions to clarify the direct and immediate nature of the delusion:

Suddenly things seem to mean something quite different. The patient sees people in uniform in the street; they are the Spanish soldiers. There are other uniforms; they are Turkish soldiers...Then a man in a brown jacket is seen a few steps away. He is the dead Archduke who has resurrected. Two people in raincoats are Schiller and Goethe ... (Jaspers, 1963)

Kurt Schneider (1887–1967), a contemporary of Jaspers at Heidelberg, subtyped delusions proper, or primary delusions, further into delusional mood, autochthonous delusional ideas and delusional perception (Wahnvorstellung). Delusional mood (Wahnstimmung), otherwise known as ‘delusional atmosphere’, refers to the ‘sense’ a person may experience that there is something ‘going on’ around them, which they cannot explain. This sense of anticipation sometimes precedes the emergence of a delusion, whereas sudden or autochthonous delusions are those that appear in the individual’s mind fully formed.

Unlike delusional mood and autochthonous delusions, delusional perception is described as a two-stage process. The first stage involves the experience of a normal perception. This is then followed by the attribution of a delusional meaning to that perception (Walker, 1991). Jaspers provides an example, namely, ‘the man in the brown jacket’, who is a real (and normal) percept but is then perceived (believed) to be the resurrected Archduke. This contrasts with the one stage, immediate nature of delusional mood and autochthonous delusional ideas.

However, there are further subtle distinctions that are noteworthy; for example, in contrast to a delusional perception, a delusion-like idea is a belief that originates understandably from experiences such as false perception, derealisation while in an altered state of consciousness or a strong emotional experience (Jaspers, 1963). For example, if a person were to believe the Archduke had been resurrected because of an auditory hallucination indicating that this was so, then they would be said to be experiencing a delusion-like idea; the deduction made, that of resurrection, is an understandable one, based on the content of the hallucination.

Phenomenologically and clinically, a categorical distinction was made between delusions and normal beliefs, because Jaspers regarded delusions proper and delusion-like ideas to be distinctly abnormal processes (McKenna, 1984). In contrast, OVI were viewed as part of normal mental life alongside normal beliefs (Walker, 1991).

Overvalued ideas

OVI were first conceptualised within psychopathology by Carl Wernicke in 1900. Prototypical disorders include the querulous paranoid state, pathological jealousy, body dysmorphic disorder and anorexia nervosa (McKenna, 1984). Initially, an OVI was regarded as a dominant and solitary belief consistent with the individual’s personality, determining their behaviour to a morbid degree. It was never considered to be senseless by the person, especially as the belief often took form following an emotionally arousing experience (McKenna, 1984). For example, a person who tends to be suspicious and perceive external attacks may take great offence to a slight injustice and begin to make complaints, before progressing to legal action. For years, the event becomes the sole focus of the person’s thinking and energy. Considering the minor nature of the original event, the person’s response is clearly disproportionate. However, the belief of injustice, while exaggerated, is neither irrational nor bizarre, and so, it is not strictly delusional.

This example demonstrates how OVI are understandable in the context of an individual’s personality and background, and how these beliefs may arise from key, life-changing events. This is unlike delusions proper or primary delusions, which are distinctly alien (McKenna, 1984). Jaspers drew the distinction between OVI and normal belief as the abnormal way in which events take on meaning in OVI (Jaspers, 1963). This description of OVI bears resemblance to the delusion-like idea, which in the original definition could also arise from a strongly charged emotional experience. Although the relationship between these two phenomena was not clarified in early descriptions, they appear to be associated concepts.

An intense emotional experience is thus necessary for the development of an OVI. This intensity may explain in part the determination with which these ideas are usually acted upon. This is unlike delusions proper, where there may be a disconnect between conviction and action, known as an inconsequential attitude or ‘double orientation’ (functioning in a normal way while holding an abnormal belief; Mullen and Gillet, 2014). Personality is also a key component in the definition of OVI and it greatly informs the understanding of the origins of the belief. Concordance between an OVI and premorbid personality style is essential. However, interestingly, the importance of context, personality and associated emotion is not included in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) definition of OVI, and similarly, it is not routinely given consideration in clinical practice. Instead, DSM-5 simply defines OVI as an unreasonable and sustained belief held with less than delusional intensity, or in other words, a less severe form of a delusion.

Returning to the original descriptions of these phenomenological terms is useful as it reminds us of their core defining features, which are insufficiently emphasised in current definitions and are meaningfully different reflecting the fact that OVI and delusions are likely distinct processes. These features include the irreducibility of delusions and the significance of personality, context and emotion in the development of OVI (see Table 1).

Table 1.

Features that define and distinguish delusions and over-valued ideas.

Belief	Core features
Delusions
Delusions proper	Ununderstandable (unverständlich) and unmediated (unmittelbar) beliefs that are held with strong conviction and impervious to experience or counter-argument.
Autochthonous delusion	Beliefs which appear fully formed in the individual’s mind, without apparent cause or antecedent (Malhi and Malhi, 2006).
Delusional mood	Wahnstimmung or ‘delusional atmosphere’. A ‘sense’ a person may experience that there is something ‘going on’ around them, which they cannot explain.
Delusional perception	Wahnvorstellung. An abnormal and incomprehensible meaning is ascribed to a normal perception.
Delusion-like idea	A belief arising understandably from false perception, derealisation or strong emotional experience.
Overvalued idea	A dominant belief, consistent with the individual’s personality, which determines their behaviour to a morbid degree. May develop following an intense emotional experience.

In clinical practice, it is important to elucidate these phenomena with these concepts in mind because it is likely to enhance the accuracy of diagnoses and inform the management of mental disorders.