“Mind-boggling! Science creates computer that can decode your thoughts and put them into words,” the Daily Mail’s headline exclaimed today, while The Daily Telegraph heralded an era in which a “mind-reading device could become a reality”.

You’d be forgiven for thinking famous mind readers such as Derren Brown had just produced a telepathy implant. Instead, these reports are from a small study of 15 people that culminated in researchers being able to reconstruct the sound patterns of words using brain activity alone.

This research involved attaching electrical sensors directly to brains of people undergoing brain surgery to understand how they processed individual words that were played to them. The researchers demonstrated that the brain breaks words down into complex patterns of electrical activity. They were then able to create a mathematical algorithm that decoded and translated the brain activity back into a rough version of the original sound.

But the reconstructed words were not of good enough quality to be recognised by a human listener when played. The words were only recognised when the original and reconstructed sound patterns were compared visually.

This exciting and new research does raise the prospect of brain activity one day being translated into words using an implant. Such technology could help the vast numbers of people suffering from problems affecting speech. But it is important to recognise that this research is in its very early stages and a clinically effective implant is likely to be a long way off.

Where did the story come from?

The study was carried out by a collaboration of North American universities led by researchers from the University of California, Berkeley. It was funded by several academic grants and was published in the peer-reviewed science journal Public Library of Science (PLoS) Biology.

The researchers report that the human brain has evolved complex mechanisms to decode highly variable sounds into meaningful elements of language, such as words. Understanding this complex decoding in humans has proved difficult, as it requires recording brain activity on the exposed brain (with the skull removed).

This study took advantage of cases of rare brain surgery for epilepsy and brain tumours that allowed researchers to measure brain activity by attaching sensors directly to the brain surface. This provided a unique opportunity to understand how the human brain recognises speech.

This study received wide media coverage due to its futuristic appeal and was often given a sci-fi angle, with some suggesting a “mind-reading device could become reality”. This research does raise the possibility of developing a device that could interpret thoughts into speech in the future. However, it is important to note the authors’ own caution – that the technology of translating thoughts into words needs to be vastly improved before such a device could become a reality.

What kind of research was this?

This was a small study of 15 people undergoing brain surgery for epilepsy or brain tumour. It looked at whether the complex brain activity involved in processing spoken words, such as the sound wave form and syllable rate, could be reconstructed using a computer program.

The researchers believe that the brain processes internal thoughts in a similar way to hearing sounds, and hope that this type of technology could eventually be used to help those who cannot talk, such as those in a coma or in the much-feared “locked-in syndrome”.

What did the research involve?

Fifteen patients undergoing brain surgery for epilepsy or brain tumour were asked to listen to 47 real or invented words and sentences from different English speakers. All patients had normal language capabilities when they were enrolled in the study.

During this process electrical signals from the brain were recorded using multiple sensors attached directly to the part of the brain called the lateral temporal cortex, which includes the superior temporal gyrus (STG), thought to be very important in the processing of speech.

To understand and mimic the brain activity involved in processing heard words, the researchers used an approach referred to as “stimulus reconstruction”. In this case, the stimulus was hearing a spoken word.

Hearing words causes a large amount of brain activity involved in recognising and processing the different aspects of the sounds of the words, for example the different sound frequencies and timing of syllables. The word reconstruction involved creating a mathematical program (like that used in computer software) capable of decoding the vast amount of brain activity in such a way that it was possible to identify the original words heard by the participant.

The reconstructed signals from different mathematical models (linear and non-linear) were compared to those detected directly from the brain surface to see how good they were at mimicking the brain’s activity when hearing spoken words. The researchers also used the models to identify the most important areas of the brain involved in processing this information and what other factors influenced the accuracy of the sound reconstructions.

What were the basic results?

When constructing the mathematical models they found that the STG region of the brain was important in creating an accurate prediction of the sound pattern of the original word.

The sound patterns generated by the mathematical model allowed the identification of specific words to be generated directly from the brain activity of patients listening to the words. These took the form of visual representations of the word sound pattern. A total of 47 words were presented in pairs and, on average, the model correctly identified the word in approximately nine out of every ten instances (89%). This was significantly better than 50% correct identification, which would be seen simply by guessing.

Importantly, however, the quality produced from reconstructing the words was not good enough for them to be recognised by a human listener when played. The words were only recognised when the original and reconstructed sound patterns were compared visually.

The researchers found that different types of mathematical models performed better at reconstructing the sounds of words with particular characteristics.

How did the researchers interpret the results?

The authors concluded that their results demonstrated that key aspects of speech signals can be reconstructed from STG activity.

Conclusion

This study of 15 people undergoing brain surgery has demonstrated a method of reconstructing the sound of a heard word using only the signals obtained from the brain. This study represents an important progression in the field of speech reconstruction, which has the potential to improve the lives of many who suffer from speech difficulties in the future.

But the words, when reconstructed, were not of good enough quality to be recognised by a human listener when played. The words could only be identified when the original and reconstructed sound patterns were compared visually. The researchers suggest that improving the brain sensors detecting the STG brain activity may, in the future, improve the reconstructed sound to a level that could be understood by a person listening.

The mathematical formula used to reconstruct the words is at a very early stage and would need a significant amount of improvement and development before it could be considered for use in an implant or similar device in the future. Similarly, future speech reconstruction research would need to demonstrate it was effective in a large range of words, sentence patterns and languages. Currently, the mathematical program has only been tested on a limited vocabulary of 47 English words.

This research represents an intriguing first demonstration of the potential of speech reconstruction technology to transform the lives of people with communication problems in the future.

Links To The Headlines

Science decodes ‘internal voices’. BBC News, February 1 2012

Mind-reading device could become reality. The Daily Telegraph, February 1 2012

Mind-boggling! Science creates computer that can decode your thoughts and put them into words. Daily Mail, February 1 2012

Mind-reading program translates brain activity into words, The Guardian, February 1 2012

Links To Science

Pasley BN, David SV, Mesgarani N, et al. Reconstructing Speech from Human Auditory Cortex. PloS Biology. Published online January 31 2012

“Heartburn pills taken by thousands of women ‘raise risk of hip fractures by up to 50 per cent’,” the Daily Mail reported today. The headline is based on a large new study of drugs called proton pump inhibitors (PPIs), which are commonly used to treat heartburn, acid reflux and ulcers.

The study found that post-menopausal women who regularly took PPIs for at least two years were 35% more likely to suffer hip fracture than non-users, a figure that increases to 50% for women who were current or former smokers. However, although this increase in risk is large, the overall risk of fractures remains small.

This was a large, well conducted study that suggests that long-term use of PPIs is associated with a small increase in risk of hip fracture, although the researchers point out that the risk seems to be confined to women with a history of smoking. Unlike previous research, this study took careful account of other factors that might affect risk such as body weight and calcium intake.

Women who are concerned about their use of PPIs are advised to consult their GP.

Where did the story come from?

The study was carried out by researchers from Massachusetts General Hospital, Boston University and Harvard Medical School and was funded by the US National Institutes of Health. The study was published in the peer-reviewed British Medical Journal.

Although the Mail’s headline is technically correct, it gives the impression that these drugs carry a very large increase in the risk of hip fracture. In fact, the study found that, in absolute terms, the increase in risk for regular users was small. Researchers found that among the women in the study who regularly used PPIs, about two in every 1,000 fractured a hip each year. In non-users, this figure was about 1.5 in every 1,000. This is a increase of about five fractures a year in every 10,000 women taking PPIs.

The Mail did point out this “absolute difference” towards the end of its story. Both the Mail and the BBC included comments from independent experts.

What kind of research was this?

The researchers point out that PPIs are among the most commonly used drugs worldwide. In the US they are available over the counter, but in the UK are available only on prescription. They are used for symptoms of heartburn, gastro-oesophageal reflux disease (GORD) and stomach ulcers. PPIs are thought to work by reducing acid production in the stomach. Concern has grown over a potential association between long-term use of these drugs and bone fractures, although the researchers say that previous studies have had conflicting results and many did not take other factors (called confounders) that might affect the risk of fracture into account.

In their cohort study of nearly 80,000 post-menopausal women, the researchers set out to examine the association between long-term use of PPIs and the risk of hip fracture. Unlike a randomised controlled trial, a cohort study cannot prove cause and effect. However, cohort studies enable researchers to follow large groups of people for long periods and they are useful for looking at potential long-term risks and benefits of treatments. The study was prospective, which means it followed participants in time, rather than collecting information retrospectively. This makes it more reliable.

What did the research involve?

This study took its data from a large ongoing US study called the Nurses Health Study, which began in 1976 and which sent health questionnaires every two years to 121,700 female nurses aged 30-55.

From 1982 participants were asked to report all previous hip fractures and in each biennial questionnaire, women were asked if they had sustained a hip fracture over the previous two years. Those who reported a hip fracture were sent a follow-up questionnaire asking for more details. Fractures from bad accidents, such as falling down a flight of stairs, were excluded from the study. A review of medical records for 30 of the women validated all self-reported fractures.

From 2000 to 2006 the women were asked if they had regularly used a PPI in the previous two years. In earlier questionnaires (1994, 1996, 1998 and 2000), the women were also asked if they had regularly used other drugs for acid reflux, called H2 blockers.

The biennial questionnaires also included questions on other factors including menopausal status, body weight, leisure activities, smoking and alcohol use, use of hormone replacement therapy (HRT) and other medicines. Researchers used a validated food frequency questionnaire to calculate the women’s total intake of calcium and vitamin D.

They then analysed the data for any association between regular use of PPIs and hip fracture, adjusting their findings for key confounders such as body weight, physical activity, smoking and alcohol and calcium intake. They also took into account whether the reasons for using a PPI might have affected the results.

Finally, they carried out a systematic review combining their results with 10 previous studies on the risk of hip fracture and the long-term use of PPIs.

What were the basic results?

The researchers documented 893 hip fractures during the period of the study. They also found that, in 2000, 6.7% of women regularly used a PPI – a figure that had risen to 18.9% by 2008.

• Amongst women who had regularly taken a PPI at any time, there were 2.02 hip fractures per 1,000 person years, compared with 1.51 fractures per 1,000 person years among non-users.
• Women who regularly used PPIs for at least two years had a 35% higher risk of hip fracture than non-users (age adjusted hazard ratio (HR) 1.35; 95% confidence interval (CI) 1.13 to 1.62), with longer use associated with increasing risk. Adjustment for risk factors, including body mass index, physical activity and intake of calcium did not alter this association (HR 1.36; CI 1.13 to 1.63).

The increased risk did not change when researchers also took into account the reasons for PPI use:

• Current and former smokers who regularly used PPIs were 51% more likely to have a hip fracture than non-users (HR 1.51; (CI) 1.20 to 1.91).
• Among women who never smoked there was no association between PPI use and hip fracture (HR 1.06; (CI) 0.77 to 1.46).
• In a meta-analysis of these results with 10 previous studies, the risk of hip fracture in users of PPI was higher compared to non–users of PPIs (pooled odds ratio 1.30; CI 1.25 to 1.36).

The researchers also found that two years after women stopped taking PPIs, their risk of hip fracture returned to a similar level to that in women who had never taken them. Also, women taking H2 blockers had a “modest” increased risk of hip fracture but the risk was higher in women who took PPIs.

How did the researchers interpret the results?

The researchers conclude that their results provide “compelling evidence” of a risk between PPI use and hip fracture. They say the findings suggest that the need for long-term, continuous use of PPIs should be carefully evaluated, particularly among people who have smoked or are still smokers.

They suggest that PPIs may increase the risk of fracture by impairing the absorption of calcium, although in this study the risk of fracture was not affected by dietary calcium intake. The finding that the risk was confined to women with a history of smoking (an established risk factor for fracture) indicates that smoking and PPIs may act together (have a “synergistic effect”) on fracture risk.

Conclusion

This large study had several strengths. Unlike some previous studies, it collected information on and took into account other key risk factors for fracture, including body weight, smoking, alcohol use and physical activity. It also looked at the women’s use of PPIs every two years (rather than just asking them once) and took into account variations in use during this time in their analysis.

However, as the authors note, it also had some limitations:

• It did not ask about the brands of PPI used, nor the doses of PPI the women took, both of which could affect risk of fracture.
• The information about hip fracture was self-reported and not confirmed by medical records (although a smaller study has found self-reporting of hip fracture to be reliable).
• Also, the study did not record the women’s bone mineral density (BMD). Low[?] BMD is an important risk factor for fracture and adding a measure of this could have strengthened the study.

Finally, because this was a cohort study, other factors both measured and unmeasured may have affected the results, even though researchers took many of these into account in their analysis. Socio-economic status and education, for example, were not established. Because this was a study of registered nurses, the applicability of the results to other socio-economic groups might be limited.

This study found that the long-term, regular use of these drugs is associated with a small increased risk in hip fracture among older women, a risk that seems to be confined to past or current smokers. Women who regularly take PPIs and who are concerned about these findings are advised to talk to their GP. Whether any change in use of this commonly prescribed drug is needed requires further study. 

Links To The Headlines

Indigestion drugs taken by millions linked to hip fractures. The Daily Telegraph, February 1 2012

Heartburn pills taken by thousands of women ‘raise risk of hip fractures by up to 50 per cent’. Daily Mail, February 1 2012

Ulcer drugs ‘link to fractures’. BBC News, February 1 2012

Links To Science

Khalili H, Huang ES, Jacobsen BC, et al. Use of proton pump inhibitors and risk of hip fracture in relation to dietary and lifestyle factors: a prospective cohort study. British Medical Journal. Published online January 31 2012