Leg length, skull circumference, and the prevalence of dementia in low and middle income countries: a 10/66 population-based cross sectional survey.
BACKGROUND
Adult leg length is influenced by nutrition in the first few years of life. Adult head circumference is an indicator of brain growth. There is a limited literature linking short legs and small skulls to an increased risk for cognitive impairment and dementia in late life.


METHODS
One phase cross-sectional surveys were carried out of all residents aged over 65 years in 11 catchment areas in China, India, Cuba, Dominican Republic, Venezuela, Mexico and Peru (n = 14,960). The cross-culturally validated 10/66 dementia diagnosis, and a sociodemographic and risk factor questionnaire were administered to all participants, and anthropometric measures taken. Poisson regression was used to calculate prevalence ratios for the effect of leg length and skull circumference upon 10/66 dementia, controlling for age, gender, education and family history of dementia.


RESULTS
The pooled meta-analyzed fixed effect for leg length (highest vs. lowest quarter) was 0.82 (95% CI, 0.68-0.98) and for skull circumference 0.75 (95% CI, 0.63-0.89). While point estimates varied between sites, the proportion of the variability attributable to heterogeneity between studies as opposed to sampling error (I2) was 0% for leg length and 22% for skull circumference. The effects were independent and not mediated by family history of dementia. The effect of skull circumference was not modified by educational level or gender, and the effect of leg length was not modified by gender.


CONCLUSIONS
Since leg length and skull circumference are said to remain stable throughout adulthood into old age, reverse causality is an unlikely explanation for the findings. Early life nutritional programming, as well as neurodevelopment may protect against neurodegeneration.
Prince
Martin
M
King's College London, Institute of Psychiatry, Centre for Public Mental Health, Health Service and Population Research Department, London, UK. m.prince@iop.kcl.ac.uk
Acosta
Daisy
D
Dangour
Alan D
AD
Uauy
Ricardo
R
Guerra
Mariella
M
Huang
Yueqin
Y
Jacob
K S
KS
Rodriguez
Juan J Llibre
JJ
Salas
Aquiles
A
Sosa
Ana Luisa
AL
Williams
Joseph D
JD
Acosta
Isaac
I
Albanese
Emiliano
E
Dewey
Michael E
ME
Ferri
Cleusa P
CP
Stewart
Robert
R
Gaona
Ciro
C
Jotheeswaran
A T
AT
Kumar
P Senthil
PS
Li
Shuran
S
Guerra
Juan C Llibre
JC
Rodriguez
Diana
D
Rodriguez
Guillermina
G
D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003462:Cuba / Q000453:epidemiology; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D003906:Developing Countries / Q000706:statistics & numerical data; D004293:Dominican Republic / Q000453:epidemiology; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007866:Leg / Q000033:anatomy & histology*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D009752:Nutritional Status; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012886:Skull / Q000033:anatomy & histology*; D012959:Socioeconomic Factors; D014687:Venezuela / Q000453:epidemiology