Getting A Head
Courtesy of Wil...
Sep 25th 2003
From The Economist print edition
Why people with large heads suffer less cognitive decline in old age
EXACTLY what the size of a person's brain means for his various abilities has been hotly debated for years. A few years ago, a study found that babies with high birth weights-who invariably have bigger heads-had better reading skills, superior reasoning and more robust memories, among other things, well into their twenties.
Christopher Martyn and his colleagues at the Environmental Epidemiology Unit in Southampton also knew that older people with big heads fared better in their golden years than those with small ones, but were hesitant to accept that most of the critical brain growth took place in utero. What might explain this connection between big-headedness and preservation of faculties in later life?
The research by Dr Martyn and his colleagues at the Environmental Epidemiology Unit is published in the October issue of Brain.
They decided to investigate by recruiting 215 male and female volunteers born between 1922 and 1930. Midwives' notes had recorded their head size at birth. They measured current head size, height and gave volunteers standard IQ and memory tests. They also screened them for depression. Three and a half years later these tests were repeated.
They found that a large adult head size was beneficial in preventing cognitive decline, in particular memory. At the other end of the spectrum, though, the news was grim. Those with the smallest heads had up to a fivefold greater risk of cognitive decline over this time than those with the largest. But, when the researchers analysed the data to see if head size at birth was protective, they found it was not, as they explain in the October issue of Brain.
Why the discrepancy? There is no denying the importance of development in the womb. The last third of pregnancy is one long growth spurt for the fetal brain. But brain growth keeps up quite a pace after the child is born as well: in the first year alone, a baby's brain doubles in weight and by the time a child is six, brain weight has tripled. At that tender age, a child's brain has already attained about 93% of its final size.
Dr Martyn's theory is thus that brain development during infancy and early childhood is more important than fetal growth in keeping the lights bright-and that those gains last well into old age
Sep 25th 2003
From The Economist print edition
Why people with large heads suffer less cognitive decline in old age
EXACTLY what the size of a person's brain means for his various abilities has been hotly debated for years. A few years ago, a study found that babies with high birth weights-who invariably have bigger heads-had better reading skills, superior reasoning and more robust memories, among other things, well into their twenties.
Christopher Martyn and his colleagues at the Environmental Epidemiology Unit in Southampton also knew that older people with big heads fared better in their golden years than those with small ones, but were hesitant to accept that most of the critical brain growth took place in utero. What might explain this connection between big-headedness and preservation of faculties in later life?
The research by Dr Martyn and his colleagues at the Environmental Epidemiology Unit is published in the October issue of Brain.
They decided to investigate by recruiting 215 male and female volunteers born between 1922 and 1930. Midwives' notes had recorded their head size at birth. They measured current head size, height and gave volunteers standard IQ and memory tests. They also screened them for depression. Three and a half years later these tests were repeated.
They found that a large adult head size was beneficial in preventing cognitive decline, in particular memory. At the other end of the spectrum, though, the news was grim. Those with the smallest heads had up to a fivefold greater risk of cognitive decline over this time than those with the largest. But, when the researchers analysed the data to see if head size at birth was protective, they found it was not, as they explain in the October issue of Brain.
Why the discrepancy? There is no denying the importance of development in the womb. The last third of pregnancy is one long growth spurt for the fetal brain. But brain growth keeps up quite a pace after the child is born as well: in the first year alone, a baby's brain doubles in weight and by the time a child is six, brain weight has tripled. At that tender age, a child's brain has already attained about 93% of its final size.
Dr Martyn's theory is thus that brain development during infancy and early childhood is more important than fetal growth in keeping the lights bright-and that those gains last well into old age