Too much Facebook = less brain cells, according to a study in the medical journal Behavioral Brain Research.

The researchers did MRI scans of active 85 Facebook users.

“Higher daily frequency of checking Facebook on the smartphone was robustly linked with smaller gray matter volumes of the nucleus accumbens,” the study said.

Nucleus accumbens are the pathway in the brain that activates during pleasurable experiences.  Apparently, Facebook doesn’t make those little guys do much activating.

It’s not the first study to show a link between social media and negative feelings.  Heavy social media users can feel inadequate in comparing their lives to others, leaving them feeling unfulfilled.  Here’s a Yale University/USC study linking excessive Facebook use to sadness.  Here’s another study that says much the same thing from Harvard.

But, wow!  This study says it’s not just that you feel bad, excessive social media use can, in effect, re-wire your brain in a bad way.

There’s even a formula for it:

For every 1% increase in the number of likes, status updates, and link clicks, happiness levels decreased by 5 to 8%.

People using 7 or more social media platforms were three times more likely to be depressed and anxious, compared to those who used two or less.

A recent study by Carnegie Mellon says that more than a third of Facebook posts express sad or negative feelings and that brought even more attention than other posts. Negative emotions got, on average, about twice the comments. Facebook users also received more private messages after sharing negative feelings.

On the flipside, giving up social media for just one week has been linked to significant increase in positive feelings.

What happened when 500 Facebook users gave it up for one week

After just one week without Facebook, the group that abstained reported a significantly higher level of life satisfaction.  Read more about what happened when 500 Facebook users gave it up for one week.

Those without Facebook reported an increase in social activity (you know, actual social activity) and an increased satisfaction with their social life in general. They found it easier to concentrate. Less stressed.