Abnormal brain fold biomarker for major depressive disorder – Neuroscience News

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Summary: Researchers have discovered a biomarker for major depressive disorder (MDD) in the outer folds of the brain, or gyri. The investigation, first, combined MDD with the local gyrification index (LGI), a measure of cortical folding derived from brain scans.

The study revealed that patients with MDD exhibit reduced cortical folding, especially in the left pars triangularis. This breakthrough lays the foundation for a better understanding of MDD and possible treatment targets.

Main facts:

  1. This study is the first to examine the relationship between major depressive disorder (MDD) and the local gyrification index (LGI) of multiple cortical regions.
  2. The researchers found that patients with MDD showed lower LGI values, indicating a decrease in cortical folding, especially in the left pars triangularis.
  3. Clinical characteristics of MDD, such as recurrence and duration of illness, are associated with increased gyrification in multiple occipital and temporal cortical areas.

source: Medical College of South Korea

In nature, the outermost layer of the human brain, called the cortex, is a maze of folded cells. The peaks or raised surfaces of these folds, called gyri, play an important role in the proper functioning of the brain.

Improper gyrification – or the development of gyri – has been implicated in various neurological disorders, one of which is the debilitating and pervasive mental illness, major depressive disorder (MDD).

This shows the head of a woman.
LGI is a measure of cortical folding obtained from brain scans as a ratio of the curved and smooth surface of the cortex in the region of interest. Credit: Science News

Although previous studies have shown that abnormal cortical folding patterns are associated with MDD, reliable indicators are still far away.

Now, on the positive side of events, researchers led by Professor Byung-Joo Ham and Associate Professor Kyu-Man Han from Korea Medical University have reported the successful identification of a neuroimaging-based biomarker for MDD in a recent study published on May 8, 2023. Psychological medicine.

Speaking about the unique findings that separate from previous studies, Prof. Ham explains, “Our first study investigated the association of MDD with the local gyrification index or LGI of the entire cortical region. The brain level and the association of LGI with the clinical characteristics of MDD.”

But what exactly is the local gyrification index (LGI)?

LGI is a measure of cortical folding obtained from brain scans as a ratio of the curved and smooth surface of the cortex in the region of interest.

In this study, researchers compared LGI values ​​from several cortical regions in the brains of patients with MDD and healthy subjects. The neuroimaging data used to compare and analyze the two groups was obtained from magnetic resonance imaging scans.

Prof. Ham and his team showed that LGI values ​​from several cortical regions in the brains of patients with MDD showed hypogyrification – a condition characterized by reduced cortical folding – compared to healthy individuals.

They found that patients with MDD showed significantly lower LGI values ​​in 7 out of 66 cortical areas evaluated (in both hemispheres of the brain), which included the prefrontal cortex, anterior cingulate cortex, insula, and more temporal and parietal regions.

In particular, the most significant hypogyrification was observed in the left triangle of patients with MDD. These findings are nothing short of a breakthrough in MDD research!

When asked to share his thoughts on the results of the study, Dr. Han confirmed that there is more to their findings than what meets the eye.

“The cortical region that we evaluated in our study has previously been shown to affect emotional regulation. This means that abnormal cortical folding patterns may be related to neural circuit abnormalities related to emotional regulation, thus contributing to the pathophysiology of MDD,” he added.

The study’s findings firmly establish that LGI is a relatively stable neuroimaging marker for MDD, compared to previously identified biomarkers. This is because the LGI value reflects the long-term development process of gyrification that is not spontaneously affected by the individual’s state during the measurement process.

It is also worth pointing out the strength of this study, since it involves a larger sample size of participants, which makes it more extensive than similar studies that have been conducted previously.

Interestingly, the researchers observed that the clinical characteristics of MDD, including the recurrence and duration of illness in patients, were associated with increased gyrification in the occipital and temporal cortical regions.

However, they did not observe significant differences in LGI values ​​in these regions between patients and control groups.

With the start of this study, future research can explore the genetic factors that predispose individuals to an abnormal cortical folding pattern, and in turn, MDD. The study can also be a road map for the selection of cortical regions as medical treatment targets aimed at reducing the symptoms of this condition.

Overall, by identifying a new biomarker for MDD, this study paves the way for a deeper understanding of this serious and pervasive mental health problem, which may hopefully bring the medical community one step closer to finding effective solutions in the future.

About this important depression research news

Author: Gihyun Park
source: Medical College of South Korea
contact: Gihyun Park – Korea University College of Medicine
Image: Image is credited to Neuroscience News

Original research: Open access.
“Decreased Cortical Gyrification in Major Depressive Disorder” by Byung-Joo Ham et al. Psychological medicine


Abstract

Decreased Cortical Gyrification in Major Depressive Disorder

Background

Early neurodevelopmental abnormalities, such as abnormal cortical folding patterns, are biomarkers of major depressive disorder (MDD). We aimed to investigate the association of MDD with the local gyrification index (LGI) in each cortical region at the whole brain level, and the association of LGI with clinical features of MDD.

method

We obtained T1-weighted images from 234 patients with MDD and 215 healthy controls (HCs). LGI values ​​from 66 cortical areas in bilateral hemispheres were automatically calculated according to Atlas Desikan-Killiany. We compared the LGI values ​​between the MDD and HC groups using analysis of variance, including age, sex, and years of education as partners. The association between clinical characteristics and LGI values ​​was investigated in the MDD group.

The result

Compared with HCs, patients with MDD showed significantly reduced LGI values ​​in cortical regions, including ventrolateral and dorsolateral prefrontal cortices, medial and lateral orbitofrontal cortices, insula, right rostral anterior cingulate cortex, and more temporal, the largest parietal cortex. Effect size in the left pars triangularis (Cohen’s f2 = 0.361; P = 1.78 × 10−13). Regarding the association of clinical characteristics with LGIs within the MDD group, recurrence and longer illness duration were associated with increased gyrification in several occipital and temporal regions, which did not show significant differences in LGIs between the MDD and HC groups.

Summary

These findings suggest that LGI may be a relatively stable neuroimaging marker associated with MDD predisposition.

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