People with larger brains also have better memory, logic and reactions, scientists have found.
The major discovery follows 200 years of attempts to confirm links between brain size and cognitive performance.
MRI scans revealed the link as scientists studied 13,600 people to discover the link between cognitive power and brain size.
A larger brain does give you better steed in tasks using memory, logic and reactions, scientists from the US and Netherlands have confirmed using data from 13,600 Britons
Researchers from the US and Netherlands compared brain size from MRI scans with cognitive performance and educational achievements.
The results of the study, published in the journal Psychological Science, are the most comprehensive example of this type of investigation and is the largest of its kind.
Lead researcher, Professor Nave, said: ‘The effect is there, on average, a person with a larger brain will tend to perform better on tests of cognition than one with a smaller brain.’
The study was based on a ‘gigantic’ new dataset containing information from more than half a million British people.
It includes information about their health and genetics as well as brain scan images from 20,000 of its participants.
Professor Philipp Koellinger at the Vrije Universiteit Amsterdam in the Netherlands and co-author of the study, said: ‘This gives us something that never existed before.
‘This sample size is gigantic — 70 per cent larger than all prior studies on this subject put together — and allows us to test the relationship between brain size and cognitive performance with much greater reliability.’
‘Substantial differences’ were found concerning the size of male and female brains but this did not affect cognitive performance.
‘Just like with height, there is a pretty substantial difference between males and females in brain volume, but this doesn’t translate into a difference in cognitive performance,’ Professor Gideon Nave, from the University of Pennsylvania, said.
Other studies reported that the female cerebral cortex—the outer layer of the front part of the brain — tends to be thicker than in males.
Professor Nave said: ‘This might account for the fact that, despite having relatively smaller brains on average, there is no effective difference in cognitive performance between males and females.’
Participants were tested on logic, memory and reaction time but not on knowledge they had acquired over time as this produced a ‘relatively noisy measure’ of general cognitive performance.
The team tried to focus on brain size alone when assessing a person’s intelligence.
These included factors such as height, socioeconomic status and genetic ancestry. Height, for example, has previously been correlated with bigger brain size.
Increased brain size was an indicator of both cognitive performance and level of educational attainment – or qualifications.
The researchers pointed out that measuring cognitive performance is a difficult task, and the study has its weaknesses.
Brain size is only a small part of the picture, they said, accounting for only two per cent of the variability in test performance.
For educational attainment the effect was even smaller. Professor Nave said: ‘An additional 100cm3 cup full (about 100ml) of brain would increase an average person’s years of schooling by less than 5 months.’
Researchers highlighted that despite their findings, nobody should be ‘measuring job candidates’ head sizes when hiring for a job.
Professor Nave said: ‘Think of a computer – if you have more transistors, you can compute faster and transmit more information.
‘It may be similar in the brain to some extent – if you have more neurons, this may allow you to have a better memory, or complete more tasks in parallel.
‘However, things are likely to be much more complex in reality.
‘For example, consider the possibility that a bigger brain, which is highly heritable, is associated with being a better parent. In this case, the association between a bigger brain and test performance may simply reflect the influence of parenting on cognition.
‘We won’t be able to get to the bottom of this without more research.’
WHAT IS A MAGNETIC RESONANCE IMAGING (MRI) SCAN?
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body.
An MRI scanner is a large tube that contains powerful magnets. You lie inside the tube during the scan.
An MRI scan can be used to examine almost any part of the body, including the brain and spinal cord, bones and joints, breasts, heart and blood vessels and internal organs – such as the liver, womb or prostate gland.
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body. An MRI scanner is a large tube that contains powerful magnets. You lie inside the tube during the scan
The results of an MRI scan can be used to help diagnose conditions, plan treatments and assess how effective previous treatment has been.
Most of the human body is made up of water molecules, which consist of hydrogen and oxygen atoms. At the centre of each hydrogen atom is an even smaller particle, called a proton. Protons are like tiny magnets and are very sensitive to magnetic fields.
When you lie under the powerful scanner magnets, the protons in your body line up in the same direction, in the same way that a magnet can pull the needle of a compass.
Short bursts of radio waves are then sent to certain areas of the body, knocking the protons out of alignment. When the radio waves are turned off, the protons realign. This sends out radio signals, which are picked up by receivers.
These signals provide information about the exact location of the protons in the body. They also help to distinguish between the various types of tissue in the body, because the protons in different types of tissue realign at different speeds and produce distinct signals.
In the same way that millions of pixels on a computer screen can create complex pictures, the signals from the millions of protons in the body are combined to create a detailed image of the inside of the body.
Researchers hope a deeper understanding of the biological underpinnings of cognitive performance can help shine a light on environmental factors that shape our intelligence.
Professor Nave said: ‘Suppose you have the necessary biology to become a fantastic golf or tennis player, but you never have the opportunity to play, so you’ll never realise your potential.
‘We’re hopeful that if we can understand the biological factors that are linked to cognitive performance, it will allow us to identify the environmental circumstances under which people can best manifest their potential and remain cognitively healthy.’
They also plan to determine whether certain regions of the brain, or connectivity between them, plays a role in contributing to braininess.
As early as in 1836, German anatomist Friedrich Tiedemann wrote in the journal Philosophical Transactions ‘there is undoubtedly a connection between the absolute size of the brain and the intellectual powers and functions of the mind.’
Since then, experts have been divided about whether he was right, with brain imaging methods such as MRI scans enabling them to make more reliable assessments of brain volume than ever before.
Previously, an international team of researchers led by the University of Vienna found a robust but weak association between brain size and IQ. Instead, they concluded that it was brain structure that mattered.
SIZE OF THE HIPPOCAMPUS COULD INDICATE RISK OF MEMORY DECLINE
Larger hippocampi – a pair of structures located in the left and right sides of the brain – could indicate a reduced risk of memory decline, a new study suggests.
The preliminary study of 226 people, published in the journal Alzheimer’s Research and Therapy, indicates that an association between brain volume, in particular the size of the hippocampi, and memory, could predict a person’s likelihood of developing dementia.
The hippocampi are responsible for forming new memories and when they are impaired, such as in Alzheimer’s disease, it becomes difficult to remember recent acts or events.
Larger hippocampi – a pair of structures located in the left and right sides of the brain – could indicate a reduced risk of memory decline
Previous studies have suggested that their size could be used as a standard assessment, indicating those at increased risk for the development of Alzheimer’s disease.
The researchers examined 226 memory clinic patients to see if there was any indication of those who may be at higher risk of developing dementia.
A total of 34 were diagnosed with Alzheimer’s disease and 82 had ‘amnestic mild cognitive impairment,’ which can be a precursor to Alzheimer’s disease.
The patients performed memory tests, including recalling lists of words and remembering geometric shapes and patterns while undergoing MRI scans.
The experts found individuals with ‘normal memory’ had larger hippocampi and performed better in memory tasks than those with cognitive impairment.
Aaron Bonner-Jackson, the lead author of the study, from Centre for Brain Health at the Cleveland Clinic, said, ‘We found that a large left or right hippocampus could indicate a better verbal or spatial memory.
‘We suggest that performance on the spatial memory task is a more sensitive measure of hippocampal volumes than performance on the verbal memory task.
‘This challenges earlier studies and clinical trials which focused on verbal memory alone, as we’re now finding that spatial memory is a bigger player in assessment of those at risk for Alzheimer’s disease.’
He added: ‘We want to detect the earliest signs of dementia and this link between the performance on standard clinical measures of memory and changes in the hippocampus could be another hallmark sign of Alzheimer’s disease.’