Syndrome of subjective doubles as a rare presentation of a first-episode psychosis

Background

Delusional misidentification syndromes (DMS) are uncommon neuropsychiatric disorders that can be defined by a set of rare delusions, in which there is a fixed false belief about the identity of a significant person like a family member or oneself, place or object and are characterised by face recognition memory impairments.1 2

These delusional syndromes are often accompanied by paranoid delusions and are not diagnostic entities per se.3

Originally, this psychopathological phenomenon was only linked to psychiatric diseases. Some authors considered DMS to be one of the most persistent psychotic symptoms in patients with schizophrenia. However, with the ever-evolving neurosciences domain and contribution from other medical specialties, such as neurology and neuroradiology (in the study of its aetiology), it is known that this phenomenon can occur in several neuropsychiatric disorders and it is accompanied by neurobiological findings that support a structural basis to DMS.4–6

These psychotic symptoms were first described by Karl Jaspers within the Delusions of Transformation (Allgemeine Psychopathologie, 1913).7 A few decades later, in 1981, Christodoulou and Malliara-Loulakaki introduced the term ‘delusion misidentification syndromes’. This group of false recognitions shared a common basis and were divided into four main subtypes: Capgras syndrome (CS), Fregoli syndrome, intermetamorphosis and subjective doubles.8

The delusion of doubles exclusively of the patient’s own self is known as the ‘syndrome of subjective doubles’ (Doppelganger), or ‘syndrome of doubles of the self’. In this syndrome, described by Christodoulou in 1978, patients believe that other people become a physical duplicate of themselves, and carry out independent actions.5

It is considered a rare phenomenon, with very few reported cases since its first description, and, within the delusional identification syndromes, is regarded as the rarest of them all.9 The short duration of misidentification syndromes in some patients may be a contributing factor to its underdiagnosis in cross-sectional studies.10

In this article, we describe the case of a patient with the syndrome of subjective doubles during first-episode psychosis. The authors intend to highlight its unique features and shed some light on this rare psychopathological phenomenon.

Case presentation

A man in his 30s with no psychiatric history was taken by a relative to the emergency psychiatry department. He was living with his family at the time and was running his own business. He had no significant medical history except for a psoriasis diagnosis and there was no family history of psychiatric illness. He reported daily cannabis consumption over a 10-year period, but did not meet criteria for DSM-V Substance Use Disorder.

A feeling that something was not quite right started approximately 3 years earlier, after a friend performed a witchcraft ritual on him. He started to exhibit signs of paranoid ideation. At work, he held a firm belief that many of his customers had something to tell him. He also believed that he could influence the results of live sport matches he watched. All of this because the witchcraft ritual was controlling him. He went on to say that a second version of himself, one that was identical in every way, had duplicated his identity 3 years earlier. Two days prior to admission, he described feeling peaceful because everything finally made sense: a mobile phone that looked exactly like his own meant that a second version of himself really existed. It was at this point when he decided to close his business and change the name used for his business affairs.

Collateral information from the patient’s family corroborated that he had been engaging in ruminative, persecutory thought patterns for a few months at least and denied any perceptible abnormality in his mood or sleep patterns.

At the time of his initial psychiatric interview, he maintained eye contact, with no psychomotor agitation or retardation. Attention, concentration and orientation were intact. He described his mood as ‘peaceful’, and his affect was congruent with his mood. His speech was noted to be slightly increased in rate, but easily interruptible when necessary. He exhibited a tangential thought process with content in line with persecutory and self-reference delusions. He did not appear to respond internal stimuli. At the time of the initial assessment, he denied any suicidality or homicidality.

Investigations

Although DMS were initially described in psychiatric patients, such presentations have been increasingly reported in patients with focal neurological lesions.

Full blood count, electrolytes, liver function tests, fasting glucose, cholesterol, triglycerides, endocrine function tests, hepatitis screen, HIV, screening for sexually transmitted diseases, vitamin measurements and ECG showed no abnormalities, except for a mild folic acid deficiency.

Urine drug screening revealed the presence of tetrahydrocannabinol (THC). Physical examination, including neurological examination, revealed no pathological findings. A CT scan of the brain exhibited standard results for the age group. Therefore, MRI was not performed. Investigations were conducted according to box 1.11

Differential diagnosis

A diagnosis of a first-episode psychosis was established, and from the brief history, it was suggested that there was a gradual onset of symptoms. The lack of neurological findings and the patient’s long-term substance use render substance-induced psychotic disorder as a likely hypothesis. However, considering the age group and chronological manifestations of positive symptoms, a possible diagnosis of schizophrenia requires a longitudinal assessment.

Treatment

The patient was admitted to the psychiatric ward and started a pharmacological treatment with daily paliperidone 6 mg per os (PO), lorazepam 1 mg PO and folic acid 5 mg PO as well as ensuring hydration, parenthetically initially and then orally, to mitigate THC withdrawals. After 5 days, paliperidone was increased to 9 mg PO daily due to the persistence of delusional paranoia.

Pharmacological treatment was combined with psychosocial interventions. Illness self-management training was included in the treatment plan, including psychoeducation, behavioural interventions to facilitate adherence and a relapse prevention plan. The patient received psychoeducation based on group cognitive behavioural therapy and motivational interviewing on addictions, and participated in inpatient activities that were available to all patients. These continued after discharge with a more structured and individual approach.

Additionally, the patient participated in occupational therapy activities such as mental exercises and training to improve cognitive performance and functional outcomes.

He received counselling on the risks of drug use, particularly cannabinoids, alcohol, stimulants and hallucinogens. The causal role of substance misuse in schizophrenia is still controversial but there is evidence that prior use of some drugs, particularly cannabis, is associated with an increased risk of developing schizophrenia later on. Cannabis use has also been shown to precipitate psychotic relapse in people with schizophrenia who had previously achieved remission and is associated with a worse outcome and reduced treatment efficacy.12

Family support and education about the illness was provided to mitigate disease burden and promote recovery.

Outcome and follow-up

In the hospital, the patient achieved full remission of delusions after 7 days with no identifiable delusions or changes in perception. His family also confirmed clinical improvement and at discharge; he was instructed to maintain daily paliperidone 9 mg PO and folic acid 5 mg PO.

One month later, at the first reassessment, the patient showed no signs of psychotic symptoms and reported maintaining abstinence from cannabinoids. He had sold his business and was in the process of starting a new job, a life change that he welcomed. The patient’s father corroborated the information. However, in the previous week, he was non-compliant with the medication because he thought it caused him muscle weakness. A reduction of the antipsychotic dosage was attempted (paliperidone 6 mg PO daily) but in the following visit, 1 month later, the patient had stopped the medication due to the aforementioned reason. A switch to another antipsychotic was proposed but the patient refused all options. Despite this, he agreed to attend a follow-up appointment. Thus, an advanced rescue plan was developed in collaboration with the family in case of relapse, with more frequent appointments and additional psychoeducation about the disease.