Physiological fitness measures and sensory and motor performance in aging.

This study investigated relationships between a multivariate index of physiological fitness and the degree of age-related sensory and motor performance deterioration observed in a group of 70 male subjects (age 63 +/- 12 years). Physiological fitness was determined by reducing a battery of resting pulmonary, hemodynamic and biochemical variables to a single score, the Index of Physiological Status (IPS). In addition, where possible, maximal oxygen uptake (VO2max) was predicted from submaximal values using a standard treadmill procedure. Both IPS and VO2 scores were significantly correlated with age (p less than .01). High scores on the IPS were associated with faster reaction times, improved hearing at high frequencies, greater phonatory control and improved lens accommodation. In contrast, VO2 measures were found to be insensitive to changes in sensory and motor performance. While all subjects were able to complete the tests required for the generation of the IPS, 33% of the participants were unable to complete the treadmill protocol required for estimation of VO2max. These data suggest that a simple noninvasive instrument for the evaluation of physiological fitness, which is applicable to almost all elderly subjects, may be more sensitive to age-related sensory and performance changes than more traditional exercise based measures which require the exclusion of less healthy subjects.

Physical fitness, cognitive performance, and aging.

The relationship between physical fitness and cognitive performance in old age is examined in the light of contemporary capacity theories of attention. It is suggested that a model of cognition based upon the notion of a declining attentional capacity with advancing age provides a valuable conceptual framework for examining the influence of physical fitness on cognitive performance in old age. A direct prediction of the model is that cognitive tasks which require effortful processing should be more sensitive to the effects of fitness than tasks which can be performed without or with minimal attention. It is suggested that future research in the area of exercise and cognition systematically manipulate the attentional requirements of the tasks selected for the evaluation of cognitive performance. The implications of such a task-dependent association between physical fitness and cognitive performance for future research are discussed.

Plasma cortisol, the dexamethasone suppression test and depression in normal adult males.

This study of 33 normal adult males investigated the nature of relationships between plasma cortisol levels and depression. Both plasma cortisol levels and responses to the Dexamethasone Suppression Test (DST) have been shown to be associated with clinical depression. However, relatively few studies have investigated the utility of either plasma cortisol measures or the DST for evaluating emotional distress in subjects without demonstrable psychiatric morbidity. The results of this study suggest that the traditional DST has little discriminatory power when used with psychologically healthy subjects. Conversely, plasma cortisol was shown to be positively correlated with clinical personality characteristics associated with emotional distress, particularly depression. These data suggest the hypothalamo-pituitary-adrenal irregularities are not only associated with clinical psychopathology but may also be related to emotional reactivity in normal, asymptomatic individuals.

Normal aging and human physiology.

This article discusses the physiological changes that accompany normal aging and current understandings of how environmental factors interact with a person's genetic mechanisms to slow or speed up the aging process. Chronological age is contrasted with biological age to illustrate the different rates and extent of anatomical changes and functional declines observed in older people of the same age, behaviors that appear to delay or reduce the inevitable progression of sensescence, the extraordinary heterogeneity of the aging population, and the complexity of the processes responsible for the consequences of human aging.

The influence of physical fitness on automatic and effortful memory changes in aging.

A cross-sectional study was carried out in order to determine the influence of cardiovascular fitness on age-related declines in cognitive performance. Forty-eight volunteers were divided into Young (n = 13, 18-27 years), Middle-Aged (n = 22, 60-65 years) and Old (n = 13, 65-88 years) groups and tested on a battery of cardiovascular, pulmonary, hemodynamic, and biochemical tests in order to assess physical fitness. Cognitive performance was evaluated by a variety of memory tasks distributed along an automatic-to-effortful processing continuum. Memory for location and frequency of occurrence were selected as representative of automatic processing, whereas, an auditory free-recall task was selected as representative of effortful processing. Age-related performance declines were observed for the free-recall task, but no such age-dependent association was observed for frequency and location memory. With regard to the influence of physical fitness; the Middle-Aged and Older participants were divided into High and Low Fitness groups and significant differences were observed between these groups for the effortful but not the automatic memory tasks. These data suggest that the relationship between physical fitness and cognitive performance in old age is task dependent. Furthermore, the apparent prophylactic effects of physical fitness on effortful memory, do not appear to extend to cognitive tasks requiring less effortful processing.

Adults who stutter: responses to cognitive stress.

The purpose of this study was to investigate the effects of speed and cognitive stress on the articulatory coordination abilities of adults who stutter. Cardiovascular (heart rate, systolic blood pressure, and diastolic blood pressure), behavioral (dysfluencies, errors, speech rate, and response latency), and acoustic (word duration, vowel duration, consonant-vowel transition duration/extent, and formant center frequency) measures for nine stutterers and nine nonstutterers were collected during performance of the Stroop Color Word task, a well-established and highly stressful cognitive task. Significant differences were found between the two groups for heart rate, word duration, vowel duration, speech rate, and response latency. In addition, stutterers produced more dysfluencies under speed plus cognitive stress versus speed stress or a self-paced reading task. These findings demonstrate that the presence of cognitive stress resulted in greater temporal disruptions and more dysfluencies for stutterers than for nonstutterers. However, similar spatial impairments were not evident. The potential contributions of the Stroop paradigm to stuttering research as well as the need for further research on autonomic correlates of stuttering are also discussed.