A short Alfred Hitchcock film has helped neuroscientists in London, Ont. to detect awareness in a Canadian who was thought to be in a purely vegetative state for 16 years.

Researchers at Western University used a specialized MRI scanner to analyze the brain activity of 12 healthy participants and two people with brain injuries as they watched a suspenseful, eight-minute clip of Hitchcock's Bang! You’re Dead, the scientists said in Monday’s issue of the journal The Proceedings of the National Academy of Sciences of the USA (PNAS).

One of the brain-injured patients is a man in his mid-thirties who hasn’t interacted with anyone in 16 years. His brain was deprived of oxygen after a blow to the chest.

"What we saw is that his brain changed at all of those key moments in the movie in exactly the same way as a healthy volunteer," said study author and neuroscientist Adrian Owen, a professor at Western.

"Essentially we were getting at consciousness. We were measuring or detecting the fact that this patient was able to follow the plot."

Measuring concsciousness

The brain of one patient with a brain injury responded like that of healthy controls while watching a short film. (Lorina Naci/Western University)

Bang! You’re Dead is about a boy who thinks he’s found a toy gun but the audience knows it is real, Owen said. The plot includes many twists and turns and elicits emotions, which the researchers realized they could use to monitor consciousness.

Owen and his colleagues have published papers on previous techniques to detect consciousness that require specialized equipment. In comparison, he said the Hitchcock version of the technique is relatively simple by scientific standards.

The patient father said he regularly took him to see movies in the hope that he might derive some enjoyment.

There was no evidence that the other subject in the study showed visual responses or executive function similar to the healthy participants, the researchers reported.

Owen cautioned that there are many limits on what doctors and scientists can do to assist patients, and they can’t be sure that patients may not respond for other reasons or in ways that are too subtle to register.

The researchers say negative findings must be interpreted with caution and can’t be used as conclusive evidence of lack of awareness. Healthy volunteers can show negative findings in functional MRI studies at times.

But Owen hopes the approach could help reveal what a patient might be thinking. If so, there could practical and ethical implications such as for a patient’s standard of care and quality of life.

Owen said he's impressed that the technique worked. Though the study only mentioned two patients, the technique has been tested on 15 individuals who, to an experienced neurologist, would appear to be in similarly vegetative states, he said. 

The team estimates that up to one in five of these patients who are thought to be in a vegetative state may in fact have some level of consciousness.

The research was funded by the Canada Excellence Research Chairs program.

With files from CBC's Amina Zafar