Impact of the mitochondrial genome on the relationship between short-term changes outdoor temperature and cognitive function

Abstract

TPS 664: Climate change: temperature effects 2, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background: Cognitive decline is a major challenge in aging populations. Older individuals show lower adaptation to changes in outdoor temperature than younger people. Therefore, it is plausible that short-term changes in outdoor temperature may affect cognition. Objectives: To determine whether cognitive function is associated to recent outdoor temperature among participants in the Normative Aging Study (NAS), a cohort of older males in Eastern New England. Because mitochondria are involved both in energy production and thermal regulation of the human body, we also evaluated whether the abundance of mitochondria (mtDNAcn) modified the association between temperature and cognitive function. Methods: The analysis included 591 participants in the Normative Aging Study, who underwent multiple visits between 2000 and 2013. Cognitive function was evaluated through the mini mental state-examination. We used apparent temperature one day before the visit, calculated from daily ambient temperature, dew point temperature, and relative humidity obtained from the National Weather Service Station at Boston Logan Airport. Mitochondrial DNA copy number was measured on buffy coat samples. Results: We found a significant interaction between temperature and age. Over 84 years of age the effect of decreasing temperature started to be associated with lower cognition (OR=1.1 95%CI 1.04-1.21 for a 1°C decrease in apparent temperature; p=0.002). Also, among individuals with lower mitochondrial DNA copy number we found a stronger association with low cognitive score (OR for the interaction=1.10 95%CI 1.03-1.17, p=0.006). Discussion: Our data show that older individuals were more susceptible to the influences on cognition of recent fluctuation in the low temperature range. Individuals with lower mtDNAcn —which may reflect lower mitochondrial mass—appeared to be less protected from the effects of low temperatures on cognition.