When Obsession and Psychosis Become Indistinguishable: A Clinical Case Report

Schizophrenia and obsessive-compulsive disorder (OCD) are traditionally regarded as distinct diagnostic entities. However, substantial psychopathological and neurobiological overlap has been increasingly recognized. Obsessive-compulsive symptoms occur frequently in patients with schizophrenia, leading to the concept of a “schizo-obsessive” subtype, although this is not formally included in current diagnostic classifications. Neuroimaging studies suggest shared abnormalities within frontostriatal circuits, including the prefrontal cortex and basal ganglia, supporting a possible common neurobiological substrate.^1,2 Importantly, obsessive-compulsive symptoms often precede antipsychotic exposure, arguing against a purely treatment-induced phenomenon and indicating a potentially distinct clinical subgroup with specific cognitive and functional characteristics requiring further investigation.²

Case Report

A 45-year-old man with no previous psychiatric history first developed obsessive-compulsive symptoms at age 29 years, characterized by marked perfectionism, rigidity, and cleaning and checking rituals, resulting in significant occupational impairment. He was treated with fluvoxamine, titrated to 300 mg/day, achieving partial remission. Neuropsychological assessment at that time revealed deficits in executive functioning, episodic memory, and working memory.

There was a 1-year interruption in psychiatric follow-up between 2021 and 2022, during which the patient reportedly worked abroad. In 2023, at age 43 years, he required hospitalization for approximately 1 month following the onset of perplexity, episodes of heteroaggressiveness, grandiose delusional ideas, increased goal-directed activity, and impulsivity, placing himself and others at risk. After discharge, he was admitted to a day hospital program, where affective instability, suicidal ideation, and persistent obsessive-compulsive symptoms were observed.

A subsequent neuropsychological evaluation demonstrated mild difficulty with sustained attention over prolonged periods and significant impairment in visual memory, particularly for complex figures, while other cognitive domains remained within expectations for age and education. Functional capacity was preserved, including instrumental and advanced activities of daily living, and professional performance remained satisfactory.

Discussion

This case illustrates the complex interface between OCD and schizophrenia, highlighting a long history of obsessive-compulsive symptoms preceding the late emergence of psychosis. Epidemiological studies indicate that 2.5%–64% of patients with schizophrenia experience obsessive-compulsive symptoms, and up to 37.5% meet criteria for OCD, with meta-analyses estimating OCD prevalence at approximately 12% and obsessive-compulsive symptoms at 30%–34%.^3–5 Around one quarter of individuals with schizophrenia report clinically significant obsessive-compulsive symptoms. Longitudinal data further suggest that a prior diagnosis of OCD increases the risk of subsequent schizophrenia.^3,6,7

The patient’s acute presentation, marked by grandiosity, impulsivity, and aggression alongside persistent obsessive-compulsive symptoms, reflects the clinical heterogeneity of this subgroup. Postdischarge affective instability and suicidal ideation are consistent with evidence indicating increased depressive symptoms and suicidality in this population.^3,7 Impulsivity may relate to deficits in inhibitory control, frequently observed in schizophrenia with obsessive-compulsive symptoms.^3,7

Neurocognitive findings are concordant with existing literature, with patients showing impairments in executive functioning, processing speed, cognitive flexibility, and memory.^3,7 Comparative studies suggest that cognitive deficits are generally more pronounced in schizophrenia than in OCD alone, particularly in visual and verbal learning, working memory, and processing speed.⁸ Despite these vulnerabilities, our patient demonstrated preserved functional capacity.

Pharmacologic management remains challenging. While selective serotonin reuptake inhibitors are commonly used to treat obsessive-compulsive symptoms in schizophrenia, typically in combination with antipsychotics, some second-generation antipsychotics, particularly clozapine and olanzapine, have been associated with the emergence or worsening of obsessive-compulsive symptoms.^3,5 In contrast, agents with predominant dopaminergic blockade, such as amisulpride and aripiprazole, appear less likely to induce obsessive-compulsive symptoms.⁹

Phenomenological differentiation between obsessions and delusions is critical: Repetitive behaviors should be considered compulsions only when driven by obsessions rather than psychotic beliefs, and intrusive thoughts should not be labeled obsessions when exclusively embedded in delusional content.^2,3,7 Insight is now recognized as dimensional within OCD.⁶ Neurobiologically, both disorders implicate cortico-striato-thalamo-cortical circuitry.^1,7

Overall, this case emphasizes the importance of carefully assessing obsessive-compulsive phenomena in psychosis and supports ongoing efforts to clarify whether this presentation represents a distinct subtype or a complex comorbidity with implications for prognosis and treatment.

Article Information

Published Online: September 8, 2026. https://doi.org/10.4088/PCC.26cr04228
© 2026 Physicians Postgraduate Press, Inc.
Prim Care Companion CNS Disord 2026;28(5):26cr04228
Submitted: March 15, 2026; accepted May 1, 2026.
To Cite: Rebelo M, Baronet P, Abrantes J, et al. When obsession and psychosis become indistinguishable: a clinical case report. Prim Care Companion CNS Disord 2026;28(5):26cr04228.
Author Affiliations: Psychiatry and Mental Health Department, Unidade Local de Saúde Santa Maria, Portugal (Rebelo, Baronet, Abrantes); Psychiatry and Mental Health Department, Hospital Lusíadas, Lisbon, Portugal (Croca).
Corresponding Author: Marta Rebelo, MD, Psychiatry and Mental Health Department, Unidade Local de Saúde Santa Maria, Lisbon, Portugal ([email protected]).
Financial Disclosure: None.
Funding/Support: None.
Patient Consent: Consent was received from the patient to publish the case report, and information has been de-identified to protect patient anonymity.