The relationships between body composition characteristics and cognitive functioning in a population-based sample of older British men

Background: Current research has established obesity as one of the main modifiable risk factors for cognitive impairment. However, evidence on the relationships of total and regional body composition measures as well as sarcopenia with cognitive functioning in the older population remains inconsistent. Methods: Data are based on 1,570 participants from the British Regional Heart Study (BRHS), a cohort of older British men from 24 British towns initiated in 1978-80, who were re-examined in 2010-12, aged 71-92 years. Cognitive functioning was assessed with the Test-Your-Memory cognitive screening tool. Body composition characteristics assessed using bioelectrical impedance analysis included total fat mass (FM), central FM, peripheral FM, and visceral fat level. Sarcopenia was defined using the European Working Group on Sarcopenia in Older People (EWGSOP) definition of severe sarcopenia and the Foundation for the National Institutes of Health (FNIH) sarcopenia project criteria. Results: Among 1,570 men, 636 (41 %) were classified in the mild cognitive impairment (MCI) and 133 (8 %) in the severe cognitive impairment (SCI) groups. Age-adjusted multinomial logistic regressions showed that compared with participants in the normal cognitive ageing group, those with SCI were more likely to have waist circumference >102 cm, BMI >30 kg/m(2), to be in the upper quintile of total FM, central FM, peripheral FM and visceral fat level and to be sarcopenic. The relationships remained significant for total FM (RR = 2.16, 95 % CI 1.29-3.63), central FM (RR = 1.85, 95 % CI 1.09-3.14), peripheral FM (RR = 2.67, 95 % CI 1.59-4.48), visceral fat level (RR = 2.28, 95 % CI 1.32-3.94), BMI (RR = 2.25, 95 % CI 1.36-3.72) and waist circumference (RR = 1.63, 95 % CI 1.05-2.55) after adjustments for alcohol, smoking, social class, physical activity and history of cardiovascular diseases or diabetes. After further adjustments for interleukin-6 and insulin resistance, central FM, waist circumference and sarcopenia were no longer significantly associated with SCI. Conclusions: Increased levels of peripheral FM, visceral fat level, and BMI are associated with SCI among older people. Distinct pathophysiological mechanisms link regional adipose tissue deposition and cognitive functioning.