The relationship between head size and intracranial volume in elderly subjects.
OBJECTIVE
To study the relationship between parenchymal head volume (PHV) and intracranial volume (ICV), and to compare the ability of these two measurements to reflect the association between maximum mature brain volume and late-life cognition.


METHODS
An elderly sample of humans with a range of cognitive functions from normality, via mild cognitive impairment (MCI) to dementia (mean age 78.6, S.D. 2.8; mean MMSE 25.4, S.D. 4.2) was examined. Head-to-head measurements of ICV and parenchymal head volume (PHV) were obtained from three-dimensional T1 weighted magnetic resonance images using automated procedures. Analyses of cognitive functions were based on continuous and categorial variables.


RESULTS
PHV explained 55% of the variance in ICV. The ratio between PHV and ICV remained constant with increasing age and cognitive impairment. Measurements of PHV and ICV yielded comparable correlations with global cognitive performance. Group differences over gender and cognitive states were equally present in ICV and PHV. The relative risks of cognitive impairment that were associated with either small ICV or PHV were comparable.


CONCLUSIONS
Measures of PHV can be considered as useful estimates of ICV and cerebral volume reserve.
Department of Psychiatry, University of Leipzig, Leipzig, Germany. henrike.wolf@neurotec.ki.se
Henrike
H
Wolf
Frithjof
F
Kruggel
Anke
A
Hensel
Lars-Olof
LO
Wahlund
Thomas
T
Arendt
Hermann-Josef
HJ
Gertz
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001921:Brain / Q000033:anatomy & histology*; D003071:Cognition / Q000502:physiology; D016001:Confidence Intervals; D003704:Dementia / Q000473:pathology; D005260:Female; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D012044:Regression Analysis