Estonian National Mental Health Study: Design and methods for a registry-linked longitudinal survey.

OBJECTIVES: The Estonian National Mental Health Study (EMHS) was conducted in 2021-2022 to provide population-wide data on mental health in the context of COVID-19 pandemic. The main objective of this paper is to describe the rationale, design, and methods of the EMHS and to evaluate the survey response. METHODS: Regionally representative stratified random sample of 20,000 persons aged 15 years and older was drawn from the Estonian Population Register for the study. Persons aged 18 years and older at the time of the sampling were enrolled into three survey waves where they were invited to complete an online or postal questionnaire about mental well-being and disorders, and behavioral, cognitive, and other risk factors. Persons younger than 18 years of age were invited to fill an anonymous online questionnaire starting from wave 2. To complement and validate survey data, data on socio-demographic, health-related, and environmental variables were collected from six national administrative databases and registries. Additionally, a subsample was enrolled into a validation study using ecological momentary assessment. RESULTS: In total, 5636 adults participated in the survey wave 1, 3751 in wave 2, and 4744 in wave 3. Adjusted response rates were 30.6%, 21.1%, and 27.6%, respectively. Women and older age groups were more likely to respond. Throughout the three survey waves, a considerable share of adult respondents screened positive for depression (27.6%, 25.1%, and 25.6% in waves 1, 2, and 3, respectively). Women and young adults aged 18 to 29 years had the highest prevalence of depression symptoms. CONCLUSIONS: The registry-linked longitudinal EMHS dataset comprises a rich and trustworthy data source to allow in-depth analysis of mental health outcomes and their correlates among the Estonian population. The study serves as an evidence base for planning mental health policies and prevention measures for possible future crises.

Effects of heat acclimation on time perception.

Cognitive performance is impaired during prolonged exercise in hot environment compared to temperate conditions. These effects are related to both peripheral markers of heats stress and alterations in CNS functioning. Repeated-exposure to heat stress results in physiological adaptations, and therefore improvement in exercise capacity and cognitive functioning are observed. The objective of the current study was to clarify the factors contributing to time perception under heat stress and examine the effect of heat acclimation. 20 young healthy male subjects completed three exercise tests on a treadmill: H1 (at 60% VO(2)peak until exhaustion at 42°C), N (at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C) following a 10-day heat acclimation program. Core temperature (T(C)) and heart rate (HR), ratings of perceived fatigue and exertion were obtained continuously during the exercise, and blood samples of hormones were taken before, during and after the exercise test for estimating the prolactin, growth hormone and cortisol response to acute exercise-heat stress. Interval production task was performed before, during and after the exercise test. Lower rate of rise in core temperature, heart rate, hormone response and subjective ratings indicated that the subjects had successfully acclimated. Before heat acclimation, significant distortions in produced intervals occurred after 60 minutes of exercise relative to pre-trial coefficients, indicating speeded temporal processing. However, this effect was absent after in acclimated subjects. Blood prolactin concentration predicted temporal performance in both conditions. Heat acclimation slows down the increase in physiological measures, and improvement in temporal processing is also evident. The results are explained within the internal clock model in terms of the pacemaker-accumulator functioning.

The compression of perceived time in a hot environment depends on physiological and psychological factors.

The human perception of time was observed under extremely hot conditions. Young healthy men performed a time production task repeatedly in 4 experimental trials in either a temperate (22 °C, relative humidity 35%) or a hot (42 °C, relative humidity 18%) environment and with or without a moderate-intensity treadmill exercise. Within 1 hour, the produced durations indicated a significant compression of short intervals (0.5 to 10 s) in the combination of exercising and high ambient temperature, while neither variable/condition alone was enough to yield the effect. Temporal judgement was analysed in relation to different indicators of arousal, such as critical flicker frequency (CFF), core temperature, heart rate, and subjective ratings of fatigue and exertion. The arousal-sensitive internal clock model (originally proposed by Treisman) is used to explain the temporal compression while exercising in heat. As a result, we suggest that the psychological response to heat stress, the more precisely perceived fatigue, is important in describing the relationship between core temperature and time perception. Temporal compression is related to higher core temperature, but only if a certain level of perceived fatigue is accounted for, implying the existence of a thermoemotional internal clock.

Links between self-reported and laboratory behavioral impulsivity.

A major problem in the research considering impulsivity is the lack of mutual understanding on how to measure and define impulsivity. Our study examined the relationship between self-reported impulsivity, behavioral excitatory and inhibitory processes and time perception. Impulsivity--fast, premature, thoughtless or disinhibited behavior--was assessed in 58 normal, healthy participants (30 men, mean age 21.9 years). Self-reported impulsivity as measured by Adaptive and Maladaptive Impulsivity Scale (AMIS) and behavioral excitatory and inhibitory processes as measured by Stop Signal Task were not directly related. Time perception, measured by the retrospective Time Estimation Task, was related to both. The length of the perceived time interval was positively correlated to AMIS Disinhibition subscale and negatively to several Stop Signal Task parameters. The longer subjects perceived the duration to last, the higher was their score on Disinhibition scale and the faster were their reactive responses in the Stop Signal Task. In summary our findings support the idea of cognitive tempo as a possible mechanism underlying impulsive behavior.