Alzheimer's patients whose heads are large have better memory and thinking skills than victims who have smaller heads, inspite of similar brain cell death due to the disease, new research has revealed.
The study appears in the journal Neurology.
Study author Robert Perneczky, of the Technical University of Munich in Germany, said: "These results add weight to the theory of brain reserve, or the individual capacity to withstand changes in the brain. Our findings also underline the importance of optimal brain development early in life, since the brain reaches 93 percent of its final size at age six."
Head size is one way to measure brain reserve and brain growth. Perneczky said while brain growth is determined in part by genetics, it is also influenced by nutrition, infections and inflammations of the central nervous system, and brain injuries.
He said: "Improving prenatal and early life conditions could significantly increase brain reserve, which could have an impact on the risk of developing Alzheimer's disease or the severity of symptoms of the disease."
For the study, 270 people with Alzheimer's disease took tests of their memory and cognitive skills and had MRI scans of their brains to measure the amount of brain cell death. Head size was determined by the circumference measurement.
The study demonstrated that larger head size was associated with a greater performance on memory and thinking tests, even when there was an equivalent degree of brain cell death. Specifically, for every one percent of brain cell death, an additional centimetre of head size was associated with a six percent greater performance on the memory tests.