Previous research has shown that young healthy adults with large brains and skull volumes are more likely to have good cognitive performance compared to those with smaller brains. However, whether this relationship persists into old age has yet to be clarified.
Dr Alasdair MacLullich and colleagues from Edinburgh University investigated the link between intracranial capacity, regional brain size and cognition in 97 men aged 65 to 70 using a range of clinical and psychological tests. Magnetic resonance imaging was performed in all participants to assess volume of the hippocampi, temporal lobes and frontal lobes. A range of cognitive tests, including Raven's Standard Progressive Matrices, the Benton Visual Retention Test, the Controlled Word Association Test, the Wechsler Memory Scale and Adult Intelligence Scale, the Rey Auditory-Verbal Learning Test and the National Adult Reading Test, were also completed.
The researchers found that the intracranial area and several regional brain volumes correlated with measures of premorbid and fluid intelligence and visuospatial memory. No correlation was observed for verbal memory or fluency, however. Intercorrelations were observed between different measures of cognition and also between measures of brain volume. Relationships between size of specific brain regions and cognition could not be deduced from the findings, and Dr MacLullich and colleagues state that the relationship between the two can best be defined in general terms.
They therefore conclude that overall brain size correlates positively with general cognitive ability in older men. In an accompanying editorial, Dr David Drachman, from the University of Massachusetts Medical School in the US, comments, "Brain size and intelligence both may be consequences of favorable conditions during embryonic, neonatal or childhood development. Head size, height and intelligence have been related to nutrition and other factors during foetal and childhood development."
Reference: MacLullich et al, Neurology 2002;59:169-174
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