Vitamin B12 and homocysteine associations with physical function measures in older adults, data from the Baltimore Longitudinal Study of Aging
In many older adults physical functioning declines insidiously as part of the normal aging process. Behavioral risk factors such as low physical activity, smoking, alcohol use, and inadequate diet and nutritional intake have been associated with increased decline in physical functioning in older adults. This dissertation aimed to assess the relationships between (1) a diet pattern related to homocysteine metabolism and physical function, (2) homocysteine concentrations and muscle strength decline, and (3) levels of vitamin B12 and homocysteine and gait speed decline in older adults ^ This was a secondary analysis of data from the Baltimore Longitudinal Study of Aging (BLSA) collected from 2004 to 2015. BLSA is an open enrollment cohort of community-dwelling adults, aged at least 20 years old. Participants in journal article 1 were aged 60 years or older and in journal articles 2 and 3, they were aged 50 years or older. The Health ABC physical performance battery was used to measure physical functioning. Muscle strength was measured via grip strength (kg) and gait speed (m/sec) was calculated from a timed 6-meter normal pace walk. Participants also completed a self-administered questionnaire about health behaviors and medical conditions, and a food frequency questionnaire. Clinical values of homocysteine, vitamin B12, and folate were measured using standard protocols. Reduced rank regression was used to create a homocysteine metabolism based diet pattern with homocysteine, vitamin B12 and folate designated as the intermediate response variables. Linear mixed effects regression was used in each journal article to account for the repeated measures design and unequal spacing between observations. Analyses were stratified as follows, in journal article 1 by age category at baseline, 60-74 and ≥75 years old, in journal article 2 by sex, and, in journal article 3 by age category at baseline, 50-69, 70-79, and ≥80 years old. ^ The average follow-up time in each journal article was 4.4 ± 2.0, 6.2 ± 2.1, and 5.4 ± 2.0 years. Participants ≥75 years old with the highest adherence to the derived diet pattern (high vitamin B12 and folate levels and low homocysteine concentration) had less decline in physical functioning (β=0.44, 95%CI: 0.19, 0.69) over the follow-up time. This association was not seen in the younger age group. In journal article 2, an increase of 1 µmol/L in homocysteine was significantly associated with a -0.15 kg (95% CI: -0.28, -0.02) change in grip strength for women and -0.18 kg (95% CI: -0.31, 0.05) change for men. Finally, in journal article 3, there was no association identified between vitamin B12 and gait speed, but there was a relationship between homocysteine concentrations and gait speed. Increasing homocysteine was associated with greater decline in gait speed in all age categories. ^ The results of these analyses suggest elevated homocysteine as well as a homocysteine metabolism based diet pattern could be related to decreased physical functioning in otherwise well-functioning older adults. Future research should explore homocysteine lowering therapies as interventions for physical function decline.^
Wilkinson, Michelle L, "Vitamin B12 and homocysteine associations with physical function measures in older adults, data from the Baltimore Longitudinal Study of Aging" (2016). Texas Medical Center Dissertations (via ProQuest). AAI10127406.