Time perception disorders are related to working memory impairment in schizophrenia

Time perception (TP) impairment in schizophrenia has been originally described by clinicians and afterwards addressed in laboratory. Previous studies generally observed that schizophrenia patients overestimate time and that their timing sensitivity is impaired. However, because of the disease cognitive impairments, no study until now allows to draw definitive conclusions about the nature of TP disturbances. The aim of this study is to isolate a genuine TP disorder in schizophrenia, i.e., a disorder that would be related to the functioning of an internal clock. The main hypothesis tested is that patients' internal clock runs faster than that of healthy controls. Twenty-five patients suffering from a first-episode of schizophrenia and twenty-five healthy controls performed an innovative task called method of dynamic stimuli, designed to measure the natural frequency (F(n)) of the internal clock, concomitant with a neuropsychological assessment. We observed no significant difference in F(n) between groups. Compared to controls, there was a marginally higher variability in time reproduction in patients. Patients' pattern of results and significant correlations between TP tasks and memory outcomes suggest that TP impairments are related to memory impairment in schizophrenia. These conclusions are supported by a growing literature showing that cognition is involved in TP in schizophrenia.