Study explores the possible link between body temperature and autism spectrum disorder

In a recent study published in the journal Scientific Reports, researchers assess the probable association between body temperature and autism spectrum disorders (ASD) among Japanese individuals.

Study: Exploring relationships between autistic traits and body temperature, circadian rhythms, and age. Image Credit: Lightspring / Shutterstock.com

Background

ASDs refer to neurodevelopmental disorders that present with social interaction deficits and behavioral irregularities, including repetitive and restricted interests. The pathogenesis of ASD reportedly involves an imbalance in excitatory-inhibitory neuronal activation.

Previous studies have reported reduced brain activity with a concomitant increase in cortical temperature, which indicates activation of inhibitory neuronal pathways by elevated temperature. Circadian rhythm disturbances have also been reported among ASD patients; however, large-scale studies investigating the association between circadian rhythm and autistic traits among the general population are limited.

About the study

In the current population-based study, researchers investigate whether low body temperatures were related to greater autistic traits and the probable modification of the association by circadian rhythm, age, and sex.

The survey-based study comprised 2,400 individuals between 20 and 70 years of age. Among the study participants, autistic traits were measured using questionnaires assessing the autism spectrum quotient (AQ), empathy quotient (EQ), and systemizing quotient (SQ), adjusting for self-documented circadian rhythm and age. The composite morning questionnaire (CSM) was completed by the participants to assess circadian rhythms.

Individuals self-documented their axillary temperatures, temperature recording time, wake-up time, and the manufacturing details of the axillary thermometer used. In addition, the participants documented variables that could affect body temperature, including the presence of cold, recording temperatures following exercise, use of antipyretic medications, and coronavirus vaccinations in the prior week. Data were obtained on participants’ age, sex, and residence, and analyzed by performing multiple regression modeling.

The survey forms were distributed twice online at different time points to verify the validity and reproducibility of the study findings. The first survey was conducted between October 23-27, 2021, whereas the second survey was conducted between January 14-19, 2022.

The team excluded individuals reporting menstruation data, measuring body temperatures without axillary thermometers, and those with outlier values for body temperature exceeding ±3.0 standard deviation (SD). Time data exceeding 24 hours were also excluded from the analysis.

Results

For surveys one and two, data were obtained for 3,227 and 3,402 individuals, respectively, residing across 47 prefectures in Japan. The data from 827 and 1,020 participants, respectively, were excluded, as they were obtained using inappropriate strategies and previously established techniques. As a result, data were analyzed for 2,185 and 2,264 individuals, respectively, for the association between ASD and bodily temperature, whereas 2,211 and 2,288 individuals for the other associations.

No statistically significant associations were observed between ASD-associated characteristics and axillary temperatures. However, a significant but negative association was observed between age and AQ that was concordant with reduced cognitive and sensory functions with advancing age. In addition, AQ scores were negatively correlated with CSM, thus indicating that individuals with greater autistic traits (greater AQ scores) had stronger tendencies at night.

Excluding female data of specific age groups yielded statistically significant associations. Significant relationships were observed in the initial survey; however, these results did not replicate in the subsequent survey, despite the survey procedures and dependable variable distribution being similar for both surveys. The differences in the two survey results were likely incidental due to artifacts from seasonal variations of atmospheric temperatures.

In accordance with previous studies, lower EQ scores, as well as higher SQ and AQ scores, were observed among men as compared to women. EQ and AQ scores were negatively correlated in the surveys, thus indicating that the autistic trait measurements used in the study were reliable. However, contrary to previous studies, SQ scores correlated positively and negatively with EQ and AQ scores, respectively.

Conclusions

Overall, the study findings showed no significant association between autistic traits and body temperature. However, individuals with greater AQ scores had stronger evening tendencies, whereas autistic traits were weaker among older individuals. These observations could improve understanding of age-associated malleability, circadian rhythm irregularities, and difficulties in performing routine activities in association with autistic traits.

Further research is needed to assess the validity of the findings using controlled conditions for bodily temperature recording and/or core temperature measurements. These studies should also consider individual-level alterations in ASD parameters, as well as brain and body temperatures, with time.

Autistic traits may be mitigated with advancing age in the general public. However, this possibility must be tested in future studies to guide the development of strategies for coping with ASD-associated characteristics and behaviors.