Health

DEPRESSION really does change the way you see the world. People with the condition find it easy to interpret large images or scenes, but struggle to "spot the difference" in fine detail. The finding hints at visual training as a possible treatment.

Depressed people have a shortage of a neurotransmitter called GABA; this has also been linked to a visual skill called spatial suppression, which helps us suppress details surrounding the object our eyes are focused on - enabling us to pick out a snake in fallen leaves, for instance.

Now Julie Golomb and colleagues at Yale University are trying to link this ability with major depressive disorder (MDD). Golomb asked 32 people to watch a brief computer animation of white bars drifting over a grey and black background, and say which way they were moving. A quicker response gave a higher score. Half of the group had good mental health, while the rest had recently recovered from depression. The latter were chosen so that medication would not interfere with the results, but Golomb thinks results from people with MDD would be similar because the condition is thought to have genetic factors.

When the image was large, the recovered volunteers found the task easier, which means they would do better in the forest scenario. But they performed less well than the other group when looking at a small image. "Their ability to discriminate fine details was impaired, which is the sort of perception that we tend to use on a daily basis," says Golomb (Journal of Neuroscience, DOI: 10.1523/jneurosci.1003-09.2009).

"Depression is often thought of as just a mood disorder," she says, "but it can impact upon eating and sleeping habits, and now we know it can even affect the way a person sees the world."

In a commentary on the study, Pascal Wallisch and Romesh Kumbhani of New York University propose that perception training could offer a therapy for people with MDD. Golomb says this could be possible, but it's unclear if training would increase levels of GABA.

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.