Cognitive function differs depending on the time of day, driven by the human body’s circadian rhythms. Clinicians and researchers need to take that into account when giving cognitive function tests to patients.
Michael Hufford, PhD, chief medical officer at e-Nicotine Technology, and colleagues examined data from eight different schizophrenia trials involving 2,032 people. Assessments were based on the MATRICS Consensus Cognitive Battery (MCCB) and were divided into five two-hour time intervals based on start time of the tests. Also, data from a pair of clinical trials involving pro-cognitive therapies for schizophrenia were analyzed to evaluate how daytime fluctuations affected signal detection.
Time of day played a significant role in composite MCCB score (P=0.002), the researchers reported in Schizophrenia Research. In the clinical trials, patients whose cognitive functioning was tested at the same time of day between baseline and follow-up had a better treatment response compared to those who were assessed at different times.
“Cognitive functioning ebbs and flows over the course of the day,” the researchers wrote. “Maintaining consistency in the time of day of cognitive test administrations between visits can help to reduce the noise introduced by circadian rhythms, thereby enhancing signal detection in clinical trials of potential pro-cognitive therapies.”
Cognition is affected by circadian rhythms over the course of a day. Circadian rhythms in cognitive functioning are driven by a variety of both endogenous and exogenous factors. Patients with schizophrenia are known to have disturbed circadian rhythms that can affect their cognitive functioning.
We examined the impact of time of day on cognitive test scores from subjects participating in clinical trials of potential pro-cognitive therapies for schizophrenia and then explored how this diurnal variation affected signal detection.
READ FULL ARTICLE