Tortured brains tell not the truth

Published in The Hindu on September 22, 2009

Contrary to popular belief, fuelled by reams of fiction, prolonged torture does not help in bringing out the truth.

The torturer’s task could well be an exercise in futility as a research study now shows that extended torture-sessions have just the opposite effect on the subjects: they could blurt out the falsehood as their memory is impaired.

Coercive interrogation of captives, including torture, for prolonged periods to make captives reveal the truth has been followed for two broad reasons. One, it is built on the notion that the information retrieved is reliable as suspects would tell the truth to end the torture. The second reasoning is that extreme stress, shock, and anxiety do not impact memory.

Despite the absence of any scientific basis, the U.S. government used torture on many suspected terrorists incarcerated in their detention centres at Abu Ghraib and Guantanamo Bay. The routine tools of torture, according to documented memos, include: waterboarding, sleep deprivation, stress positions, forced stripping, hooding, cramped confinement, use of diapers even in those who had no problems of continent.

A study published online on Monday (Sept. 21) in the journal Trends in Cognitive Science proves that coercive interrogation does the opposite.

Neuroscientific models show that prolonged periods of stress can impair the functioning of the parts of the human brain that are very essential to preserve memory: the hippocampus and the prefrontal cortex. This can also result in impaired memory.

The role of hormones

At the root of this dilemma for the brain is the continuous exposure to stress-hormones, which are essential in all humans to trigger the fight-or-flight response. Hormones such as cortisol and others, are released when a person is under stress. This, if expressed over extended periods, can be detrimental to the functioning of the brain.

The study, by Shane O’Mara, Trinity College Institute of Neuroscience, Ireland, says that the presence of stress hormones if “overly-prolonged, may result in compromised cognitive neurobiological function (and even tissue loss)” in the two regions of the brain that are critical to human memory.

This is because the hippocampus and the prefrontal cortex are rich in neurons, and the stress hormones released by the body will, through a series of steps, lead to compromising the normal physiological functioning of neurons.

Another set of chemicals (catecholamines) modulates many sites in the brain, and through several physiological changes bring about certain responses. According to the paper, these responses are beneficial over the short-term, but can damage the brain and body if this state of hyperarousal is maintained over long-term.

Memory disorders

Dr. O’Mara also says that several studies show that chronic, prolonged and extreme stress affects memory formation, causes long-term depression, impairs learning as the hippocampus undergoes atrophy and causes neuropsychiatric disorders.

Extreme stress can also cause frontal lobe disorders, which, in turn, results in the production of false memories (confabulation). Several studies in stressed soldiers have shown a clear link between stress and signs of impaired recall of previously-learned information. Studies also show that elevating the levels of cortisol through medication “impairs memory retrieval in humans,” just like prolonged physiological stress does.

While mild stress can generally facilitate recall, the author states that extreme form of stress over a prolonged period of time does the opposite.

The torturer’s toolkit, far from forcing subjects to reveal the truth can cause considerable damage to the human brain. The desired result remains elusive, and worse, the “truth” revealed through extended torture-sessions could well be misleading.

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