The decline of strength with age has often been attributed to declining muscle mass in older subjects. To investigate factors which might influence changes in strength across the life span, grip strength and muscle mass (as estimated by creatinine excretion and forearm circumference) were measured in 847 healthy volunteers, aged 20-100 years, from the Baltimore Longitudinal Study of Aging. Cross-sectional and longitudinal results concur that grip strength increases into the thirties and declines at an accelerating rate after age 40. However, the grip strength of 48% of subjects less than 40 years old, 29% of individuals 40-59 years old, and 15% of subjects older than 60 did not decline during the average 9-year follow-up. Grip strength is strongly correlated with muscle mass (r = .60, p less than .0001). However, using multiple regression analysis, grip strength is more strongly correlated with age (partial r2 = .38) than muscle mass (partial r2 = .16). Additionally, a residuals analysis demonstrates that younger subjects are stronger and older subjects are weaker than one would predict based on their muscular size. Thus, while strength losses are partially explained by declining muscle mass, there remain other yet undetermined factors beyond declining muscle mass to explain some of the loss of strength seen with aging.

Objective. To examine the association between selfreported knee pain and radiographic features of osteoarthritis (OA) of the knee. Methods. A sample of participants in the BaltimoreLongitudinal Study of Aging (452 Caucasian males and 223 Caucasian females) completed questionnaires and underwent a standing radiograph of both knees at the same biennial visit between 1984 and 1989. Radiographs were interpreted using both the Kellgren-Lawrence and individual features scales. Odds ratios were calculated for the association of radiographic features with knee pain after adjustment for age, sex, and body mass index.Results. Overall, 156 123%) persons reported ever having knee pain, and 104 (15%) -reported current knee pain (within the previous year). Both ever knee pain and current knee pain were significantly associated with the presence of definite knee OA (KeJlgren-Lawrence grade 22) and with the presence of all individual features. There was a direct relationship between all measures of severity of radiographic OA and knee pain.Conclusion. These data demonstrate that radiographic features of knee OA are significantly associated with knee pain. The data also support the continued use of the Kellgren-Lawrence grading scale for defining knee OA in population studies.

In the 1950s, the incidence of amyotrophic lateral sclerosis (ALS, or Lytico) and parkinsonism-dementia complex (PDC, or Bodig) on the island of Guam was much higher than anywhere else in the world. From the late 1960s to the early 1980s, the incidence of both disorders has decreased. The objective of the present study was to ascertain whether the decreasing incidence continued until the end of the century (1999). The average annual incidence of ALS and PDC was calculated for each 5-year period from 1940 to 1999, utilizing registration records of all ALS and PDC cases on Guam during that period. The results of this study confirmed that the incidence of ALS declined steadily during the past 40 years. The incidence of PDC also declined until the late 1980s but, unlike ALS, showed a slight increase from 1980 to 1999. The rapid decrease in incidence is not likely to be due to genetic factors. Instead, it is most likely to be the results of radical socioeconomic, ethnographic, and ecologic changes brought about by the rapid westernization of Guam.

The greater hip fracture rate among elderly women is generally ascribed to differences in femoral neck strength between the sexes. Strength of a given bone is a function of both its material properties and the magnitudes of mechanical stresses within it. This study examined the hypothesis that these apparent strength differences between the sexes are due to dissimilarities in the restructuring of the femoral neck with age, which result in higher stresses in elderly women. Using Hip Strength Analysis, a computer program developed by the authors, femoral neck cross-sectional geometric properties for stress analyses were derived from bone mineral image data of 409 community living, white subjects ranging from 19 to 93 years of age. Though both sexes show declines in femoral neck bone mineral density (BMD) and cross-sectional area with age, only females show a decline in the cross-sectional moment of inertia (CSMI, a geometric index of bone rigidity). The lack of decline in male CSMI appears to be a result of a small but significant increase in femoral neck girth. Similar age-related changes have been observed in the femoral shaft by others. The net effect of these observed changes is that mechanical stresses in the femoral neck of females appear to increase at three times the rate per decade of those of males. These results lend support to the hypothesis that the higher fracture rate in elderly women is due, at least in part, to elevated levels of mechanical stress, resulting from a combination of greater bone loss and less compensatory geometric restructuring with age.

Bilateral asymmetry in the structure of the second metacarpal was examined in relation to functional hand dominance in a large, clinically nonselected, healthy population sample from the Baltimore Longitudinal Study of Aging. Bilateral bone measurements were made from anteroposterior hand radiographs of a total of 992 individuals, 609 males and 383 females, with an age range of 19-94 years. Hand dominance was determined on the basis of personal impression. Total width and medullary width at the midshaft of the second metacarpal were measured to 0.05 mm using a Helios caliper. These two measurements were used to derive cortical thickness, cortical bone area, periosteal (total) area, medullary area, percent cortical area, and the second moment of area in the mediolateral plane. In both right and left-handed individuals, statistically significant side differences were found in the calculated bone areas and the second moment of area, with the dominant hand being larger. Cortical thickness did not show significant side-related differences for either handedness. These results show that functional handedness leads to periosteal and endosteal expansion of the second metacarpal cortex on the dominant side, increasing bone strength without increasing cortical thickness. This is the first time this pattern of asymmetry has been reported in left-handers as well as right-handers. Our results argue for the primacy of environmental (mechanical) effects in determining bilateral asymmetry of limb bone structural properties.

Advancing age, rather than declining serum levels of IGF-I, appears to be a major determinant of life-time changes in body composition and BMD in women and men.

Objective. To evaluate the familial aggregation of osteoarthritis (OA) in a cohort of healthy volunteers drawn from a community setting.Methods. Hand radiographs obtained between 1978 and 1991 and bilateral standing knee radiographs obtained between 1984 and 1991 were read for changes of OA, using Kellgren-Lawrence (K-L) scales. The hand sites were distal interphalangeal (DIP) joints, proximal interphalangeal (PIP) joints, and first carpometacarpal (CMC1) joints. For each joint group, the presence of OA in at least 1 joint in a joint group, the number of affected digits in each joint group, and the sum of the K-L grade across all joints were analyzed. Polyarticular OA was recorded if there were OA findings in 2 of 3 hand joint groups plus 1 or both knees. Data from 167 families with hand radiographs, 157 families with knee radiographs, and 148 families with both hand and knee radiographs were analyzed for sib-sib correlations.Results. After adjustment for age, sex, and body mass index, clinically relevant sib-sib common correlations were found for OA of the DIP, PIP, and CMCl joints, for OA at 2 or 3 hand sites, and for polyarticular OA (r = 0.33-0.81) when OA was defined according to the number of affected joints or as the sum of the K-L grade across all joints.Conclusion. These results from a cohort of volunteers drawn from a community setting and ascertained without regard to OA status demonstrate familial aggregation of OA and contribute to the evidence for heritability of OA.Familial aggregation of Heberden's nodes and of generalized osteoarthritis (GOA) have been demonstrated previously in studies of pedigrees of OA probands (1-4) For Heberden's nodes, sisters of fcmalc probands were affected nearly 3 times as often as expected, and this increased frequency was noted beginning in the fifth decade of life (1). In studies of GOA, the frequency of OA was nearly twice as high in OA pedigrees as in the general population; this increased frequency of GOA in relatives occurred beginning in the fifth decade of life in women and the sixth decade in men, and upper limb joint OA was morc prevalent than lower limb joint OA (2-4). Families for these studies of Heberden's nodes and GOA familial aggregation were selected on the basis of having at least 1 affected proband, and this ascertainment scheme may have resulted in biased estimates of thc familial aggregation. However, a recent genetic study of female twins who were ascertained without regard to OA status also showed evidence of OA heritability (5). The present study was undertaken to determine if familial aggregation of hand OA or polyarticular OA occurs in subjects drawn from a community setting, ascertained independently of OA status. SUBJECTS AND METHODSStudy population. All subjects in this study were participants in the Baltimore Longitudinal Study of Aging

Two hundred thirty-five (235) normal male participants of the Baltimore Longitudinal Study were classified as right handed, left handed, and ambidextrous on the basis of their grip-strength performance. Their left and right hands were also radiographed and the measurements of the second metacarpal bones were evaluated on the basis of hand dominance. The results indicated that, as a rule, the right hand measurements are higher than those of the left hand, regardless of hand dominance. The bilateral differences in total width, length, total area and cortical area are significant among the right hand dominant and nonsignificant among the left hand dominant. Regardless of hand dominance the bilateral differences in medullary width are nonsignificant. These results suggest an inherent tendency of the right second metacarpal to have more bone than the left regardless of hand dominance. Differential stress due to hand dominance will increase the bilateral difference in the right handed and reduce it in the left handed.