Changes in posed facial expression of emotion across the adult life span.

The purpose of this study was to examine changes in the facial expression of emotion across the adult life span. Two positive and two negative emotional expressions were posed by 30 young (21 to 39 years), 30 middle-aged (40 to 59 years), and 30 older (60 to 81 years) healthy, right-handed women. Photographs of the four emotional expressions were rated by independent judges for intensity, accuracy, and confidence. Special features of this study were the use of a neutral face as a nonemotional control, as well as careful cognitive and affective screening procedures for posers and judges. Overall, the expressions of older posers were rated as significantly less accurate and with significantly less confidence than those of younger posers. Although the neutral faces of older posers were rated as significantly more intense than those of younger posers, there were no significant age-related intensity differences for positive and negative emotions. The results are discussed in terms of theoretical models of aging.

Variability and reliability of single serum IGF-I measurements: impact on determining predictability of risk ratios in disease development.

In recent years, a number of investigators have studied the relationship between IGF-I and risk of developing cancer, diabetes or cardiovascular disease. Upper tertile, quartile, and quintile IGF-Is were associated with higher risk of developing cancer, and lowest quartile with cardiac disease and diabetes. As part of a study to correlate serum IGF-Is and growth hormone dynamics in aging, we measured fasting serum IGF-I at baseline and two weeks later in a group of 84 normal volunteers between the ages of 50 and 90 years. Although the correlation between the two IGF-Is was high (r=0.922; p<0.0001) there were substantial differences between the two IGF-I values ranging from -36.25 to +38.24% between individual IGF-I values at the two blood draws and a significant difference between the mean IGF-Is at visits I and 2 (mean 120.28+/-53.5 vs. 114.95+/-50.03; p=0.03). When considered in quartiles, IGF-I changed from one quartile to another in 34/84 (40.5%) of the volunteers. When the group was divided in halves, tertiles,quartiles, or quintiles there was an increasing number of subjects who changed from one subdivision to another as the number of gradations increased. These results suggest that the predictive outcomes of earlier studies that used single IGF-I samples for analysis of risk ratios according to tertiles, quartiles, or quintiles could have been different if a second IGF-I was used to establish the risk ratio. The results also suggest that variability in IGF-I should be taken into account when designing such studies.