Abstract
Language plays a central role in the assessment of individuals with psychosis, from taking a medical history to evaluating cognitive function. However, speaking multiple languages can significantly influence linguistic, cognitive and neural substrates. Therefore, it is essential to know whether an individual with psychosis is bilingual. Leaving modulating effects of bilingualism in psychosis unconsidered, runs high risk of confounding any clinical assessment and research. Although more than half of the world is bilingual, to date, this risk has not been addressed. This critical review challenges current basic diagnostic practices in psychiatry that conflate language and other cognitive domains. Drawing on neuropsychology, psycho-/neurolinguistics, and cognitive neuroscience, we (i) identify potential contact points between bilingualism and psychosis, (ii) present a decision tree framework for the clinical and research setting to systematically study those contact points, and (iii) provide the basis for developing and testing new treatments considering the lived realities of the majority of individuals with psychosis, namely bilingual individuals, and leveraging modern technology to do so. If the field of psychiatry embraces these conclusions, not only could bilingual individuals with psychosis experience more equity, but the larger field would benefit by reducing confounds inherent to ascribing to monolingual assumptions.