Cogan’s syndrome and treatment-resistant psychosis

To the Editor

Cogan’s syndrome (CS) is a rare autoimmune disease, characterised by ocular disease, interstitial keratitis and vestibuloauditory dysfunction with 10% developing visual impairment and 52% developing hearing loss, which is typically bilateral and progressive (Gluth et al., 2006).

Mr K is a 46-year-old man diagnosed with CS in 2011 after developing anterior uveitis and hearing loss. He was treated with Prednisolone, topical corticosteroids and the immunosuppressant mycophenolate but still developed bilateral sensorineural hearing loss and significant visual impairment. Mr K was diagnosed with autism and intellectual disability as a child. Since 1991, Mr K experienced psychotic episodes consisting of ‘bad thoughts’, obsessional behaviours, images of Jesus in his mind together with non-specific paranoid ideation. He maintained remission on a combination of Olanzapine and Flupenthixol Decanoate. However, following CS onset, his psychosis progressed accompanied by new-onset auditory and visual hallucinations with more persistent and severe persecutory delusions. Mr K was subsequently commenced on Clozapine, and this led to significant improvement with residual visual and auditory hallucinations.

In the published literature, there have been 250 cases of CS and only two cases associated with psychosis (Gluth et al., 2006; Raese and Ibrahim, 2015). There is an established late paraphrenia literature describing the role of sensory impairment in the development of psychosis in later life (Osvaldo et al., 1995). There is evidence to suggest that pre-existing brain conditions might play a role in the development of late-onset psychosis (Raese and Ibrahim, 2015). Given Mr K’s autism, intellectual disability and previous psychotic episodes, it is possible that these pre-existing conditions resulted in him developing treatment-resistant psychotic symptoms. In addition, the different phenomenology and treatment resistance following onset of CS could be directly associated with CS, the sensory loss secondary to CS or due to a combination of these factors and his autism.

Currently, the link between CS and psychosis is not well established. Given the low prevalence of CS, it is possible that an association between CS and psychosis has yet to be established. Possibly, this case may add to the increasing evidence of a link between the autoimmune conditions and schizophrenia. This case also suggests that the onset of sensory impairment in people prone to psychosis may lead to worsening of pre-existent psychosis, different phenomenology (in particular perceptual disturbances) and treatment resistance.