PESSIMISM IS GENETIC according to a new study, which suggests levels of a certain chemical in the brain influences how we think and feel.

Those who are often told to ‘look on the bright side’ of things could have lower levels of a molecule called neuropeptide Y (NPY), which tends to make people view life without rose-coloured glasses. Those with low levels of the molecule tend to be more pessimistic and get stressed more easily.

More seriously, those with low levels of  NPY are also more likely to suffer from depression reports WebMD.

The Telegraph reports that researchers from the University of Michigan used functional magnetic resonance imaging (fMRI) to monitor the brain activity of volunteers as they were read words with neutral, positive or negative connotations. Those with low levels of NPY displayed greater activity in the prefrontal cortex – the area of the brain which deals with emotion.

Subjects were then given a pain challenge, in which they were required to recount a controlled painful experience. Volunteers were injected in the jaw with saline solution, which caused moderate pain for about 20 minutes but no lasting harm. They were then asked to rate the level of pain on a scale of one to 10.

Those with low levels of NPY were more negative both before and after the experience, meaning they were more emotionally affected by it.

Lastly, scientists compared the NPY genotypes of subjects with major depressive disorder with control subjects; they found that those with low levels of the molecule were more likely to suffer from a depressive illness.

See the full report in the Archives of General Psychiatry.