Circadian variation and seasonal differences in occurrence of acute ischemic strokes

Abstract

Morocco is a country with clear seasonal variations in weather conditions. Seasonal and circadian variations in the occurrence of cerebrovascular diseases have been of interest in several studies, reported to climate changes, but discrepant results made the conclusions unclear. The aim of the study is to observe the seasonal and circadian variation in ischemic stroke onset among our population. This is an observational study based on cases of stroke recruited from a prospectively collected database, conducted between January 2018 and December 2018 in the Department of Neurology, at Ibn Rochd university hospital. All patients with a diagnosis of ischemic stroke and having a definitive time and month of onset were included in the study. The categorization of the year was distributed into months and seasons. The time of onset was subdivided into one hourly interval and 4 quadrants of 6 hourly intervals. A total of 363 patients were included in the study. Mean age of patients was 66 years. Male to female ratio was 1,14. The rate of occurrence of stroke was highest in the morning 06 h–12 h hours (p < 005) compared with other times of the day. It was lowest in the nighttime period 00 h–6 h quadrant compared with other quadrants (Fig1). Annual distribution of stroke was without any variation. No difference was found by dichotomizing the groups into four 3 month periods (Fig2).These data support the presence of a circadian pattern in the onset of stroke, with a significantly higher risk in the morning, probably explained by the circadian changes in pathophysiologic causes of stroke.