Evidence map›Paper›PMID 42365273›Full record

ArticleBMC psychiatry2026

Delusional parasitosis with shared psychotic features secondary to vitamin B12 deficiency and mild cognitive impairment: a case report.

Chiyoko Bando, Naomichi Okamoto, Enkhmurun Chibaatar, Satoru Ide, Reiji Yoshimura, Atsuko Ikenouchi

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In one paragraph

Article in BMC psychiatry, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

What it found

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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

6 authors.

Chiyoko BandoDepartment of Psychiatry, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan.
Naomichi OkamotoDepartment of Psychiatry, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan. nokamoto@med.uoeh-u.ac.jp.ORCID https://orcid.org/0000-0003-2791-8113
Enkhmurun ChibaatarDepartment of Psychiatry, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan.
Satoru IdeDepartment of Radiology, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan.
Reiji YoshimuraDepartment of Psychiatry, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan.
Atsuko IkenouchiDepartment of Psychiatry, University of Occupational and Environmental Health, Kitakyushu, 8078555, Japan.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundVisual illusions are misperceptions of real external stimuli and, when persistent, may indicate underlying neurological or metabolic disorders. Delusional parasitosis is characterized by a fixed belief of infestation without medical evidence and may occur secondary to medical conditions. However, the relationship between visual illusion-related perceptual abnormalities and delusion formation, particularly in reversible metabolic states such as vitamin B12 deficiency, remains unclear. CASE PRESENTATION: An 80-year-old man presented with a persistent belief that mites infested his body and environment. His delusion was preceded by misinterpretation of real stimuli, including lint and skin debris, consistent with visual illusions. Cognitive assessment indicated mild cognitive impairment. His wife gradually came to share his delusional beliefs. Laboratory findings revealed marked vitamin B12 deficiency. Brain perfusion imaging demonstrated hypoperfusion in the medial occipital and parietal association cortices. Treatment with low-dose quetiapine and mecobalamin resulted in rapid resolution of visual illusions and subsequent disappearance of delusional parasitosis. Quetiapine was discontinued without relapse, and follow-up imaging showed improvement in cerebral perfusion. The wife's shared beliefs resolved following clinical improvement and separation.

conclusionsThis case suggests that visual illusions due to reversible metabolic disturbances may precipitate delusional parasitosis in cognitively vulnerable individuals and highlights the importance of evaluating all suspected patients and closely associated individuals.

Indexed as

Cognitive DysfunctionDelusional ParasitosisShared Paranoid DisorderVitamin B 12 DeficiencyAged, 80 and overAntipsychotic AgentsHumansMaleQuetiapine FumarateVitamin B 12Antipsychotic AgentsmecobalaminQuetiapine FumarateVitamin B 12Case reportDelusional parasitosisShared psychotic disorderVisual illusionVitamin B12 deficiency

Identifiers

PMID42365273
PMCPMC13579725

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.