London: The number of Facebook friends a person has seems to be linked to the grey matter in his or her brain. Research also shows people who have more online friends are also likely to have more 'real-world' friends.

Facebook, a social networking site, has more than 800 million active users worldwide, which includes nearly 30 million in the UK, the journal Proceedings of the Royal Society B reports.

The size of these networks varies considerably, with some users having only a handful of online friends whilst others have over a thousand, according to a University College London (UCL) statement.

Geraint Rees, professor at the UCL, and colleagues at the UCL Institute of Cognitive Neuroscience and the Welcome Trust Centre for Neuroimaging studied the brain scans of 125 university students - all Facebook users.

They found a strong connection between the number of Facebook friends an individual had and the amount of grey matter in several regions of the brain. Grey matter is the brain tissue where the processing is done.

One of these regions was the amygdala, a region associated with processing memory and emotional responses.

A recent study showed that the volume of grey matter in this area is larger in people with a larger network of real world friends. The new study shows that the same is true for people with a larger network of online friends.

Rees said: "Online social networks are massively influential, yet we understand very little about the impact they have on our brains. This has led to a lot of unsupported speculation that the internet is somehow bad for us.

"Our study will help us begin to understand how our interactions with the world are mediated through social networks."

"This should allow us to start asking intelligent questions about the relationship between the internet and the brain - scientific questions, not political ones," he added.

(Agencies)