Delusional disorder

Diagnostic formulation #

Delusional disorder concerns a persistent delusional presentation without the broader syndrome that would better support another psychotic disorder. Evaluate cultural context, real adversity and the possibility that the belief is true. Ordinary conversation and preserved functioning outside the concern do not resolve that assessment.

Targeted assessment #

Ask neutrally about the belief, conviction, distress, time occupied and attempts to obtain evidence or protection. Clarify confrontation, checking, spending, complaints, approaching another person and effects on relationships. Assess self-harm and harm to others directly rather than deriving either from the theme of the belief.

Important alternatives #

Distinguish schizophrenia-spectrum illness, mood-related psychosis, cognitive or neurological illness, substance or medicine effects, and obsessive-compulsive-related disorders with poor insight. A fixed appearance or health belief may belong to another syndrome when its wider features explain the presentation.

Investigations and physical assessment #

Assess hearing, vision, cognition, neurological change, medicines and substances as indicated by the history. Late onset or a change from baseline strengthens the need to investigate secondary causes. A negative test does not itself demonstrate that a belief is delusional.

Treatment and recovery #

Begin with a working alliance around distress and practical goals. Avoid ridicule or an argument intended to force admission that the belief is false. Specialist care may consider psychological treatment and a medication trial; the evidence base is more limited than for schizophrenia and does not justify importing its entire prescribing pathway.

Doses & prescribing #

Each prescribing record identifies its population and source jurisdiction; international labeling does not establish Indian approval. The clinician selects treatment after assessment.

No category-specific dose schedule has been verified for this chapter. General psychosis guidance is not sufficient to choose a drug, formulation or dose.

When progress is limited #

Review engagement, the agreed treatment target and whether intervention has reduced distress or harmful behaviour even if conviction persists. Reconsider an underlying neurological, mood or obsessive-compulsive-related syndrome. Repeatedly changing medicines without checking exposure and goals may further reduce trust.

Continuing care and discontinuation #

Agree continuing review of distress, relationships and behaviour. A stable belief may still have changing consequences during conflict or loss. Any medicine continuation or reduction needs an individual review of benefit and adverse effects; a universal category-specific duration is not supplied here.

Age and population considerations #

In older adults, include cognitive, sensory and physical assessment. In younger people, review developmental and family context with specialist input. When two people share a belief, assess each separately and consider their practical dependence and support needs rather than assuming the same formulation for both.

Follow-up priorities #

Track actions, distress, preoccupation, sleep and function alongside conviction. Reassess access to the person or situation at the centre of a jealousy, persecution or erotomanic belief. Record changes in circumstances and the response plan without interpreting a quiet interview as a declaration of safety.

Clinical pitfalls #

Do not classify an unfamiliar cultural belief, reported discrimination or a contested allegation as delusional without assessing context and evidence. Do not promise that proving the belief wrong will resolve the illness. Preserve a respectful distinction between validating distress and endorsing the belief.

Current guidance context #

NICE general psychosis guidance informs specialist assessment and coordinated care; it does not supply a disorder-specific prescribing schedule for this chapter. Child and adolescent assessment follows a separate specialist pathway.

Assessment tools #

Choose the instrument for its intended purpose; interpretation accompanies the linked tool.

Patient discussion #

Related terminology #

Search terms: paranoia, folie a deux, shared delusion. These terms may differ between classifications; the diagnostic formulation above explains the chapter scope.