By AnalyzeDirect Staff, last updated March 17, 2016
Brain asymmetry refers to the asymmetrical function and structure of the brain. Each hemisphere is specialized in certain tasks and specific areas process particular types of cognitive information. Structurally, the two halves of the human brain are slightly different, in fact some structures may be larger or smaller on one half of the brain than the other.
Certain structural changes are easily observed on CT and MRI scans. For instance occipital bending, which takes place in the occipital lobe – the most posterior lobe of each cerebral hemisphere – and consists of one of the occipital lobes crossing the anterior-posterior axis and wrapping around the other lobe.
As abnormalities in brain asymmetry have been suspected to be involved in the development of psychiatric disorders, the concept that patterns of brain asymmetry might be a biomarker for these conditions has been investigated for some years.
In a study published in Brain, researchers hypothesized that occipital bending may differentiate healthy control subjects and patients with major depressive disorder and, namely, that the occipital bending angle may be greater in patients than in control subjects.
One of the underlying ideas is that this asymmetry could be the result of abnormally enlarged lateral ventricles, channels that carry cerebrospinal fluid through the brain, which lead to occipital lobe displacement. The twisted occipital lobes could be putting pressure on the hippocampus preventing it from growing properly and ultimately upping the chances of someone developing depression.
The investigators performed MRI scans of the brain of 51 people with and 48 without major depressive disorder. The scans that presented occipital bending were manually processed using Analyze software through the use of the Calipers feature, which yielded degrees of deviation. The results showed that about 35 per cent of those with depression and 12.5 per cent of the healthy control subjects showed signs of occipital bending. The difference was even greater in women than men: 46 per cent of women with this mental health disorder presented occipital bending compared with just 6 per cent of those without depression. This finding proves that females with major depressive disorder are more likely to have occipital bending than males affected by the same condition.
The results of this study showed that occipital bending is three times more prevalent among patients with major depressive disorder. Although many other factors might affect the presence of this brain asymmetry over and above depression per se, this study provides impetus for future research in major depression.Tags: Brain Asymmetry, Depression, Hippocampus, Neurodevelopment