A lab test that discloses a state of mind would take psychiatry to new levels, says S.Ananthanarayanan.

Deficiency in nutrition can be associated with changes in mood and behaviour. Pathological tests can also indicate, or at least explain some mind related symptoms. The principal use of lab tests, however, is to assess physiological conditions and the mental health clinician needs to be guided mainly by what a patient himself or herself says or communicates.

Mental illness, however, has serious social consequences when individuals become depressed, dysfunctional or violent. Suicide, usually the result of acute psychological distress, is reported as the second most frequent cause of death of young persons. The report by Marcel Adam Just, Lisa Pan, Vladimir L. Cherkassky, Dana L. McMakin, Christine Cha, Matthew K. Nock and David Brent from the Universities of Carnegie Melon, Pittsburgh, Florida, Columbia and Harvard, in the journal, Nature Human Behaviour, of a brain scan that can identify suicidal tendencies, is hence of significance.

“…suicidal patients may disguise their suicidal intent as part of their suicidal planning or to avoid more restrictive care. Nearly 80% of patients who die by suicide deny suicidal ideation in their last contact with a mental healthcare professional. This status identifies a compelling need to develop markers of suicide risk that do not rely on self-report,” the Nature paper says.

The study uses functional Magnetic Resonance Imaging (fMRI) as a brain scan to identify areas in the brain that were stimulated by exposure to different concepts, to see if there was a correlation in the responses, to words associated with depression or death, of a group of persons known to have suicidal tendencies, as opposed to a control group. Functional MRI is a non-invasive technology that detects differences in the blood flow in different areas of the brain. Words related to different concepts provoke activity, and hence blood flow, in specific area of the brains. For instance, the paper explains, the word ‘spoon’ leads to activity in the part of the brain associated with motor functions, as spoons are manipulated, and in the gustatory area, as spoons are used for eating. The word, ‘house’, on the other hand, stimulates the regions related with shelter and location.

This ‘neural signature’ of words and concepts is common and reproducible among normal people, the paper says. Testing with the neural response to concepts like ‘hate’ and ‘hug’ has been 97% accurate in making out persons suffering from autism, it says.

The study hence examined whether the brain regions that responded to positive, negative and suicide-related concepts were different in the case of persons who harboured thoughts about suicide, as compared to persons who did not. And if so, whether there was a pattern in the differences, so that an assay of the brain areas, during the time that different concepts were presented to participants, could result in accurately classifying them as suicidal or not

This line of investigation was suggested by the observation that suicidal persons show a change in concepts formed, as revealed by measurable behaviour, in response to different words. One such is the difference in reaction time to suicide-related words as compared to neutral words. Another is of reaction times in response to pairing suicide-related words and self-related words. It has been found that persons who have attempted suicide may process certain concepts or concept pairs in a different way

Building on this finding, the study sought to discover patterns in the locations or sets of locations where activity was affected by specific concept stimuli and whether there was a significant difference between suicidal individuals and others. In addition to such neural signatures, the study tried to identify their ‘emotion component’. This was with the help of an existing library of neural signatures and the associated emotions, in healthy, normal people. The library contains, for instance, neural signatures associated with emotions of ‘sadness’, ‘shame’, ‘anger’, ‘pride’ and it was taken that the nature of emotions stayed the same with suicidal and non-suicidal persons.

Trials were then conducted with two groups, balanced in respect or sex ratio, age and intelligence, of seventeen persons who harboured suicide-related thoughts and seventeen others who did not. Thirty stimuli concepts (shown in the table) were presented, for three seconds each, to the subjects. After several presentations of the stimuli, the locations in the brain where the stimuli repeatedly evoked activity were recorded, as shown in the picture.

Given 36 concepts and many locations of brain activity, correlating the data with ‘suicidal or non-suicidal’ can be a daunting task. The job was hence assigned to a machine learning classifier procedure which can handle ‘Big Data’. These algorithms, known as ‘data mining’, are routinely used to extract patterns that are concealed within huge numbers of figures. For instance, the data of credit cards used at a supermarket contains information of the categories of people who buy particular products – which could enable effective advertising and provisioning.

The result of the exercise was that the locations of brain activity could be classified with 0.85% accuracy – or 14 of the 17 suicidal and 15 of the 17 non-suicidal participants being correctly identified. Within the suicidal group, those who had attempted suicide could be separated. “Interpretable, clinically meaningful differences existed in the individuals in the suicidal ideator and control groups, and within the suicidal ideator group, there were differences between the attempters and the non-attempters,” the report says. “The specific concepts that were altered in people with suicidal ideation — 'death', 'cruelty', 'trouble', 'carefree', 'good' and 'praise' — include items from all three stimulus categories: one that is suicide-related, two that are negative, and three positive concepts,” the report says. “..and six of the concepts and five of the brain locations provided the most accurate discrimination between the two groups.”

The findings have immediate value in quickly identifying possible suicides in a population through a simple brain scan. This could help reduce the number of suicides, which is said to be 800,000 each year, worldwide. While the technique could be used generally to deal with neuropsychiatric disorders, it could, conceivably, be used as a wider diagnostic tool, given the undeniable connection between the psycho and the soma.

A question that arises, however, is what does this ability imply, outside its medical applications. The manner in which the brain physically responds to emotions or words and concepts can now be discovered. A brain scan, carried out to treat a migraine patient, may hence also reveal something personal about how she thinks. This may enable the use of brain scans for non-therapeutic ends, and may require regulation.

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