India no longer needs to pitch its brain against the global standard based on a Caucasian brain to assess psychiatric illness
An Indian brain template for five distinct age groups as well as a brain atlas to help accurate assessment of psychiatric illnesses and conduct neuro-surgical operations have been developed by neuroscientists at the Bengaluru-based National Institute of Mental Health and Neuro Sciences (NIMHANS).
The significance of this study is that neuroscientists need not be dependent upon the current universal standard of using the Montreal Neurological Index (MNI) template.
The MNI was developed by averaging Caucasian brains. Over a period of time, neuroscientists discovered that Caucasian brains are different from Asian brains. The Chinese have their own scale to measure. So do the Koreans and the French, among others.
“What has been developed is a scale that will measure an Indian brain. It is like developing a scale to measure the height or weight of a person. We cannot use a scale that is meant to measure a Caucasian to measure an Indian,” Vivek Benegal, Professor of Psychiatry, Centre for Addictive Medicine, NIMHANS, told The Lede.
The NIMHANS-India Brain Template (IBT) has been developed by a team consisting of Dr Bharat Holla, Assistant Professor, Psychiatry, Prof Rose Dawn Bharath, Department of Neuroimaging and Interventional Radiology, and Professor Benegal.
Said Dr Holla: “No two brains are alike. In fact, there is now an upcoming field of fingerprinting of the brain. When you are mapping a brain, you need to have a reference brain. It is necessary also to look at it from the perspective of ethnicity and it should also be age specific. This will prevent your final analysis becoming less accurate.”
In the case of neurosurgery, for instance, it will help in more accurately identifying the size of a tumour in the brain. “Psychiatric disorders happen because there is a difference in how some brains grow. Circuits in the brain are determined by the structure of the brain. So, a proper mapping of the brain structures helps in making a more accurate assessment,” said Professor Benegal.
He said: “The brain atlas points to a specific description of the structure and function of the brain. The brain is a 3-dimensional structure with a lot of hills and valleys. An Indian brain will have different hills and valleys as compared to, say, an American. The atlas gives much more precise measurement of the brain when things go awry.”
The NIMHANS team has developed five brain templates for age groups ranging from 6 to 60 for both males and females based on the study of nearly 500 brain scans. In each of the groups, 41 to 47% of the scans studied are that of females.
The age groups are divided in the 6-11 years (late childhood), 12-18 years (adolescence), 19-25 years (young adulthood), 26-40 years (adulthood) and 41-60 years (late adulthood).
The idea of studying the scans of brains in various age groups was because “there is a period of remarkable change that occurs from early adolescence to young adulthood (till about 25). It is a process called pruning. The thickness of the cortex starts reducing. Till about 5 to 6 years, the size of the brain increases. As exposure to various kinds of environment increases, the grey matter gets pruned, then stabilises and very gradually starts reducing,” said Dr Holla.
“Some regions show remarkable variability and similarity. For example, the frontal and parietal regions and lateral, frontal and super parietal regions in the brain are variable even within a homogenous population. A recent paper from China also found a similar pattern,” according to Dr Holla.
Given that India is multi-ethnic, would the size and type of brain also differ?
Dr Holla said: “There is a genetic study by Dr Partho Mazumdar’s team which has identified four or five different genetic structures. There are a large number of people who have more than one genetic structure. Yes, there is a North East cluster, an Andaman cluster as well. We have good representation from different zones of the country in our study.”
Professor Benegal said most of the input on children has come from a major international collaborative effort which is the “largest neuro-developmental cohort in India and one of the largest in the world. It was started using the Isaac Newton-Homi Bhabha award. This is an Indo-UK award which NIMHANS got for C-VEDA,” said Professor Benegal.
The C-Veda or Consortium on Vulnerability to Externalizing Disorders and Addictions (C-VEDA) project investigates if environmental and genetic risk factors in industrialised countries and emerging societies shape brain function and behaviour, leading to risk factors like substance misuse and externalising disorders.
The project is funded by the Indian Council of Medical Research (ICMR) and the Newton Grant From the Medical Research Council (MRC), UK.