When synesthesia and savant abilities are mistaken for hallucinations and delusions: contribution of a cognitive approach for their differential diagnosis

Abstract

Objective: Schizophrenia is characterized by hallucinations, delusions, disorganized speech and behavior, and other symptoms that cause social or occupational dysfunction. However, some of these symptoms, such as hallucinations and delusions, can be indicative of other phenomena such as synesthesia and savant abilities. The aim of this paper is to highlight how neurological and psychiatric conditions can be confused and how formal neuropsychological evaluations can be necessary to distinguish them. Method: We report the case of a young woman, VA, who perceived sounds as colors and claimed to have elaborated complex astrophysical reasoning, despite having experienced difficulties at school, especially in mathematics. VA also had difficulties to orient herself, to develop social relationships, and often became confused by daily life situations. These elements were considered as symptoms of schizophrenia. Results: Evaluations revealed that VA exhibited savant abilities in astrophysics and colored-hearing synesthesia. We also found evidence of higher-than-average cognitive functioning. Conclusions: In complex cases, neuropsychological and formal evaluations are necessary to establish a differential diagnosis. Moreover, the case highlights the link between synesthesia and savant abilities.

Keywords:

• Schizophrenia
• synesthesia
• savant abilities
• differential diagnosis

Acknowledgments

We are greatly indebted to VA, who consented to her data being used for research and publication. We also thank Jean-Michel Hupé and an anonymous reviewer for their helpful comments on the manuscript.