Aging, gender, and the elderly adult brain: an examination of analytical strategies.
We sought to examine the relations between age, gender and brain volumes in an elderly population; we also sought to examine ways of measuring these relations. Three sets of analyses were used: correlational analyses, in which correlations between independent variables and brain volumes were calculated without correction for intracranial volume (ICV); covariational analyses, in which ICV was used as a covariate in regression equations; and ratio analyses, in which the dependent variable was the ratio of brain volume to ICV. These analyses yielded similar results, except that (as expected) adjusting for ICV altered estimates of gender differences. Analyses of age showed decreases in left caudate, putamen, and right hippocampus and an increase in CSF, a result generally in accord with previous findings. However, we also found a significant decrease of white-matter volumes and no significant decrease in total gray-matter volumes. Correlational analyses showed that men did not always have larger volumes despite their larger head size; women generally had larger volumes after adjusting for ICV. We found no age-gender interactions.
Greenberg
Daniel L
DL
Psychology Department, University of California, 1285 Franz Hall, Box 951563, Los Angeles, CA 90095, USA. dlgreenberg@mednet.ucla.edu
Messer
Denise F
DF
Payne
Martha E
ME
Macfall
James R
JR
Provenzale
James M
JM
Steffens
David C
DC
Krishnan
Ranga R
RR
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012727:Sex Characteristics