Finding a physical cause behind mental health disorders is no simple task (Image: Design Pics Inc/Rex)

There’s a new twist in mental health. People with depression seem three times as likely as those without it to have two brain lobes curled around each other.

The brains of people with depression can be physically different from other brains – they are often smaller, for example – but exactly why that is so remains unclear.

In humans, some studies point to changes in the size of the hippocampi, structures near the back of the brain thought to support memory formation.


“There are so many studies that show a smaller hippocampus in almost every psychiatric disorder,” says Jerome Maller, a neuroscientist at the Monash Alfred Psychiatry Research Centre in Melbourne, Australia, who led the latest work looking at brain lobes. “But very few can actually show or hypothesize why that is.”

Mind-bending research

Maller thinks he has stumbled on an explanation. He had been using a brain stimulation technique known as transcranial magnetic stimulation as a therapy for antidepressant-resistant depression.

This involved using fMRI scans to create detailed maps of the brain to determine which parts to stimulate. While pouring over hundreds of those maps, Maller noticed that many of them showed signs of occipital bending. This is where occipital lobes – which are important for vision – at the back of the brain’s left and right hemispheres twist around each other.

So he and his colleagues scanned 51 people with and 48 without major depressive disorder. They found that about 35 per cent of those with depression and 12.5 per cent of the others showed signs of occipital bending. The difference was even greater in women: 46 per cent of women with depression had occipital bending compared with just 6 per cent of those without depression.

Reduced activity

Gerard Bruder, a clinical psychiatrist at Columbia University in New York City, says the anatomical findings may relate to findings by his team and others which show reduced electrical activity in the occipital brain regions of patients with major depressive disorder, although the mechanism at work is still unclear.

Maller thinks the brain twisting could be the result of abnormally developed ventricles, channels that carry cerebrospinal fluid through the brain.

The twisted occipital lobes could in turn be putting pressure on the hippocampus, he says, preventing it from growing properly and ultimately upping the chances of someone developing depression.

Journal reference: Brain, DOI 10.1093/brain/awu072