Human psychobiology in Scandinavia: II. Psychoneuroendocrinology—human stress and coping processes

This paper reviews psychoneuroendocrine research on stress and coping in Scandinavia during the last two decades. Two laboratories in Stockholm, led by Marianne Frankenhaeuser and Lennart Levi, respectively, have played a particularly important role for the development of this research area, where interest is concentrated on two neuroendocrine systems, the sympathetic-adrenal medullary and the pituitary-adrenal cortical systems. Stress research in Scandinavia first followed the pioneering work by Cannon and focussed on the adrenal medullary system and the secretion of the two catecholamines adrenaline and noradrenaline. The adrenal cortical system and the secretion of the corticosteroids (cortisol), which is the basis of Selye's formulations on stress and the “general adaptation syndrom”, has been studied too, during the last 10 years. During the 1960's, pharmacological experiments were performed in order to explore the relation between psychological and physiological arousal. Psychophysiological arousal was related to performance efficiency, subjective well-being, and social adjustment. In the beginning of the 1970's systematic relationships were demonstrated between psychosocial stimulation and neuroendocrine activity. Later, the modifying influence of cognitive factors on these relationships was examined in experimental studies performed in the laboratory as well as in natural settings. The results were fitted into theoretical models, describing the possible mechanisms involved in the relationship between psychosocial stress, psychoneuroendocrine response patterns and mental and physical health. During the last decade, parallel research has been carried out in the laboratory and in real life situations. A specific Scandinavian contribution has been the combination of social psychological and psychobiological strategies in the examination of stress at the work place. Another major line of research has been the study of sex differences in psychobiological stress responses.     

Type A behaviour in pre-school children: Interrater reliability, stability over six months and subcomponents

Type A behaviour was measured in 250 boys and 245 girls (ages 3-7) using a Swedish version of Matthews' Youth Test for Health (MYTH). In addition, speech and voice characteristics (speed, loudness, response latency) were measured. Each child was independently rated by two play group leaders and measurements were repeated after a six month interval. Interrater reliability (first session) was 0.76 for both sexes and did not change with the age of the child. Boys obtained significantly (p less than 0.0001) higher scores than girls. Correlations over the six month period were 0.64 and 0.60 (p less than 0.001) for the two possible combinations of different raters and slightly higher (0.75 and 0.68, p less than 0.001) when the same rater was used. Two components of Type A behaviour were identified from a factor analysis of the data: impatience and competitiveness, and they accounted for 57% of the total variance. As for the total scale, boys obtained significantly higher scores than girls on both subscales. Scores on the competitiveness scale increased systematically with age. Speech and voice characteristics correlated significantly with Type A scores (total Type A behaviour: r = 0.50, using different raters, and 0.71, using the same raters, p less than 0.001) and, once again, boys obtained significantly (p less than 0.001) higher scores than girls. The results are in close agreement with the American findings from the original scale. It was concluded that the scale provides a reliable and valid instrument for measuring Type A or Type A-like behaviours in pre-school children.     

Facial reactions to auditory stimuli: Sex differences

This study explored whether males and females differ in facial muscle activity when exposed to tone stimuli with different intensity. Males and females were repeatedly exposed to 95 dB and 75 dB 1000 Hz tones while their facial electromyographic (EMG) activity from corrugator and zygomatic muscle regions were measured. Skin conductance responses were also measured. It was found that 95 dB but not 75 dB tones evoked increased corrugator activity. This effect differed significantly between males and females. Thus, it was only females that reacted with a significant increased corrugator response to the high intensity tone. While facial responses differed between the sexes, the skin conductance response patterns did not. Consistent with previous research it is concluded that females are more facially expressive than are males.     

Dark adaptation of foveal cones during the cone-plateau period

Following substantial bleaching by "white" light, absolute threshold, relative spectral sensitivity and sensation of hue of monochromatic lights were measured at the central fovea during the cone-plateau period. The absolute-threshold level was found to increase and then decrease markedly, the relative spectral sensitivity remained invariant, while the sensation of hues of monochromatic lights from the long- and middle-wave regions of the spectrum changed toward hues of shorter wavelengths.     

Familial similarity in Type A behaviour and physiological measurements as related to sex

Thirty-one families with pre-school children were examined with regard to Type A behaviour and cardiovascular and neuroendocrine measurements. Type A scores (MYTH) of the children from the ages of three to six were positively correlated with independent Type A measurements (Jenkins Activity Survey, Bortner Type A scale) of the parents (significant for fathers but not for mothers). The children's resting systolic blood pressures were significantly correlated with maternal and paternal values, while no significant familial aggregation was found for diastolic blood pressure, heart rate, catecholamine or cortisol excretion. The children's systolic and diastolic blood pressures and adrenaline excretion were significantly correlated between ages three and six. The results are consistent with the assumption that genetic as well as environmental factors contribute to the development of Type A behaviour. No significant association was found between Type A scores and physiological measurements during routine activities in the children or the adults.     

Risk perception and the location of a repository for spent nuclear fuel

This study investigates lay people's reactions to a repository for nuclear waste. Risk perception is seen as a complex concept, comprising both affective and cognitive components. Attitude towards nuclear power and trust in experts and authorities had a substantial impact on risk perception, while personal knowledge about nuclear waste disposal had no effect. Thus, the more positive one's attitude towards nuclear power is and the more trust one has in experts and authorities, the lower one's risk perception is. Also, reactions were expected to vary with distance between the home district and the location of a repository. These variations differed in nature for people with alternative levels of risk judgement. The distance between the home and a repository affected approval of the proposed site. Distance between home and repository also had an effect on risk feelings and somewhat less on beliefs about consequences. Estimated total risk was directly mediated by beliefs about consequences, but even more so by risk feelings. With regard to risk, one can conclude that it is important to make a distinction between an emotional and a cognitive component of risk perception.     

The total workload of male and female white collar workers as related to age, occupational level, and number of children

A questionnaire assessing various aspects of paid as well as unpaid forms of productive activity was mailed to stratified samples of male and female white collar workers, approximately matched for educational and occupational level. Data from 501 men and 679 women employed full time revealed traditional gender differences in terms of main responsibility for household duties, child care etc. In keeping with this, women reported higher levels of work overload, stress and conflict than men, which increased significantly with the number of children at home. The various stress indices reached a peak between the ages of 35 and 39. Men reported more autonomy in their paid work whereas women reported more control at home. Men and women at the upper managerial levels reported more control over their total work situation and less conflict between demands.     

Early precursors and enabling skills of reading acquisition

Research on early linguistic precursors and enabling skills of reading acquisition among young children is reviewed. Language development starts early in infancy when the child learns to categorize the speech sounds according to the pattern typical of the mother tongue. Equipped with these sound categories the child is ready to learn to segment words from the sound stream and to understand and to use words. The precise phonological representation of words will facilitate the important development of phonological awareness, a basic prerequisite for reading acquisition. This paper reviews some of my longitudinal research and training studies indicating the causal direction of the relation between phonological awareness and reading and includes some ongoing studies, where gender differences, socio‐economic factors, dose‐response‐effects and motivational factors are explored. Preventive and remedial implications of the findings are pointed out. Finally, the complexity of the causal relationships between different aspects of early language development, including genetic influences and later reading is pointed out.     

Dark-adaptation of the human rod system: A new hypothesis

Following a long, full bleach, rod dark-adaptation curves from two normal trichromats were obtained with test fields of various size, exposure time and retinal eccentricity. The results show that there is a substantial region of threshold recovery with an approximately constant, linear slope of about 0.27 log per minute of dark-adaptation, which is independent of the test variables. It is suggested that the increase in sensitivity during this constant, linear slope is completely determined by changes in the concentration of bleached rhodopsin. The relationship between change of relative threshold (T) and fraction of bleached rhodopsin ( B ) is given by T=B ^3,7. This exponential law is well described by the displacement of the equilibrium between the active and inactive states of an allosteric enzyme built as a tetrarner.     

Mechanisms of long-term dark adaptation

It has previously been suggested that long-term dark adaptation is controlled by bleaching signals that regulate the activity of an allosteric, positively cooperative protein (Stabell et al., 1986a, b). Recent biochemical evidence strongly supports this assumption, indicating that the primary regulator of the light-sensitive channels in the plasma membrane of the outer segments of the photoreceptors is a homo-oligomeric, allosteric, positively cooperative protein. In this report, we discuss the possibility that signals from bleached photopigments may control the dark-adaptation process through the allosteric protein of the plasma membrane. It is suggested that the concentrations of the bleached photopigment and of the allosteric effector are reciprocal quantities.