When you’re a leftie living in a right-handed world, you know that certain common things just don’t work for you—like a “regular” pair of scissors, which works only in the right hand. But you probably don’t know that there are certain medical treatments that not only won’t work for you…they may be dangerous for you just because you are left-handed. And even some doctors may not realize this.

These treatments are not for some exotic condition, either—they are used for depression and anxiety. Several non-invasive “brain stimulation” technologies are now available to treat depression and anxiety that haven’t responded well to other therapies, and they are becoming more widely used. They employ magnets or electrical currents to increase activity in the part of the brain in the left hemisphere that is strongly linked with happiness and other positive emotions…and to decrease activity in the area of the right hemisphere responsible for negative emotions such as sadness, fear and distrust. But this one-size-fits all approach could actually harm lefties by worsening their depression and anxiety.

Why? Most research done on brain stimulation has involved only right-handed people. Yes, stimulating the left side of the brain is correct for right-handed folks, but not for left-handed ones because the two distinct emotional centers are reversed in a leftie’s brain.

To study the idea of reversing the location of therapeutic brain stimulation for left-handed people, researchers at Cornell University recruited 30 healthy individuals whose “handedness” ranged from strongly right-handed to strongly left-handed. Pain-free electrical current was applied to the frontal cortex of each participant for 20 minutes a day for five days of testing. The researchers found that when righties were stimulated on the left sides of their brains, they said that they experienced an increase in positive emotions, and so did lefties who were stimulated on the right sides of their brains. In contrast, when righties were stimulated on the right side…or lefties stimulated on the left side, they experienced an increase in negative emotions.

Surprising finding: The study also showed that brain stimulation might be a waste of time for people who are ambidextrous, meaning they neither identify as a strong leftie or strong rightie…a person who may, for example, write with his right hand but buckle a belt with his left or vice versa. This is because such people’s brain emotion centers are spread out over both brain hemispheres and can’t be precisely targeted by a current.

Research involving participants with mental health disorders is needed to validate the findings, but if they hold, these results could change the way depression and anxiety are treated. Special left-handed approaches might also be developed for other types of brain conditions such as stroke or brain injury.

In the meantime, if your health-care provider suggests brain stimulation and you’re left-handed or ambidextrous, share these findings and have a candid discussion with him/her about whether you’re truly a good candidate for the procedure.