Sexual precocity: sex incidence and aetiology

The aetiology of 197 girls and 16 boys presenting with sexual precocity was reviewed. Ninety one girls and four boys had central precocious puberty (M:F 23:1); a cause was identified in all the boys but in only six girls. All boys with precocious puberty need detailed investigation; in girls investigation should be based on clinical findings, particularly the consonance of puberty.     

The analysis of behavioural control over cardiovascular activity using pulse transit time methodology

Pulse transit time has been employed to explore a number of issues in voluntary control, including the differentiation of contingent and non-contingent fluctuations in cardiovascular activity, the patterning and the discrimination of responses. The relationship between transit time and blood pressure is discussed in the light of recent data concerning the sensitivity of intracardiac pre-ejection period and pulse wave velocity to psychophysiological procedures. Finally, the use of transit time biofeedback and relaxation in the control of cardiovascular reactions to challenging cognitive tasks is described. Analysis of individual differences in reactivity suggests that hyper-reactors may especially benefit from these treatments.     

The learned control of differential temperature in the human earlobes: preliminary study

Eight subjects were given six training periods during which they were provided with visual and auditory feedback of the temperature difference between their ears. By the end of the training, mean temperature changes of 0.3 °C were produced. Muscle activity was controlled and measured, and is not thought to have mediated the effect.     

Biofeedback and instructions in the modification of total respiratory resistance: An experimental study of asthmatic and non-asthmatic volunteers

The ability of asthmatic and non-asthmatic subjects to exert voluntary control over pulmonary function was assessed in a short-term experimental context. Total respiration resistance (R_¹ was monitored using the forced oscillation technique with a Siemens Siregnost FD5, while peak flow (PF) and forced expiratory volume (FEV₁) were also recorded periodically. Sixteen non-asthmatic and eight asthmatic volunteers attended one introductory and four experimental sessions. Each experimental session consisted of four 3-min trials, during which the participants tried to lower airways resistance, separated by rest periods. The asthmatic subject, and eight of the non-asthmatics, were provided with visual and auditory analogue feedback of R_t throughout each trial in all sessions. The second non-asthmatic group attempted voluntary control without feedback (instruction only) in sessions 1 and 2, and feedback was subsequently introduced for the final two sessions.

Analysis of sessions 1 and 2 indicated that R_t was lower in thenon-asthmatic given feedback compared with those in the instruction condition. During the final two sessions, differences between the two non-asthmatic groups disappeared. Trends also emerged within sessions, since R_t was higher in trials than rests early in sessions, while later this pattern was reversed. The average change between trials 1 and 4 in the last session was 7.1%. These effects were reflected to a limited extent in PF data.

The asthmatic response was more variable. Two members of this group produced consistent decreases in R_t of 15–20% during trials compared with rests, while modifications in the reverse direction were recorded in two others. Patients may therefore have to be carefully selected for this approach to asthma management. The mechanisms responsible for these responses are uncertain.     

Physiological correlates of cognitive functioning in an elderly population

Cognitive decline in old age is not universal or inevitable. Associations have been observed with neuroendocrine function, but the relevance of other physiological processes is unclear. We predicted that impairment of memory in an ageing population would be related to the dysregulation of neuroendocrine and cardiovascular responses. One hundred and thirty-nine participants (65-80 years) were recruited from general practice in London. Two standardised verbal paired-associates recall tasks were administered in order to determine declarative memory performance, and a fluid intelligence task (matrix reasoning) was also performed. Salivary cortisol samples were collected every 10 min, while blood pressure and heart rate were measured before, during and after each task. Illness history and medication use were obtained from medical records. Multiple linear regression analysis, adjusted for age, gender, education, chronic illness, and medication use, revealed that cortisol responses were inversely related to memory performance. Additionally, superior memory was associated with more effective post-task recovery of heart rate (in both men and women) and diastolic blood pressure recovery in men. Cardiovascular recovery effects were independent of covariates, and of levels of heart rate and blood pressure measured during tasks themselves. These associations were also independent of subjective ratings of stress and perceived performance. Neither neuroendocrine nor cardiovascular responses were related to performance of the reasoning task. We conclude that memory in the elderly is associated both with hypothalamic-pituitary-adrenocortical function and cardiovascular regulation. Disturbances of neuroendocrine and hemodynamic function may be related to greater vulnerability to cognitive decline.