Encephalon 67 raises a toast

The 67th edition of the Encephalon psychology and neuroscience carnival has just appeared online, this time put together by the Neuroskeptic blog.

A couple of my favourites include Neurophilosophy on the neuroscience of phantom limbs – apotemnophilia, missing after amputation or additional to the normal four, and a couple of good posts on the neuropsychology of religious belief from NeuroWhoa!.

There’s plenty more where those came from, so do go and check out the latest edition.

Link to Encephalon 67.

Hallucinating roman chariots and goats in overcoats

Image by Flickr user hans s. Click for sourceI’ve just found a description of some spectacular and fantastical hallucinations from a case of Charles Bonnet syndrome, reported in a review article on the neuroscience of this curious hallucinatory state.

It’s one of the most florid cases I’ve ever come across and the experience seems both wondrous and terrifying in equal measure:

A 73-year-old woman who lived alone presented with anxiety-provoking visual hallucinations. Inch-long black ants scurried across her kitchen floor, walls and windows. In desperation, she began spraying insecticide throughout the house. Her neighbour, whose features were seemingly masked by the insects, called an ambulance. Floating seahorses and featherless chickens joined the colonies of ants in the Emergency Department.

A Roman chariot, the rider dressed in gold, flashed across the curtain several times. On the ward, tropical vines grew from the foot of her bed. A man stood with thick brown tree trunks for legs and thick green branches for arms. Nurses’ heads would shrink and then expand before melting into the floor. Brightly coloured fairies carrying wands invited her for walks around the hospital grounds.

She once caught herself telling them to get off a road at which point they donned diamond coats, jumped into a wooden carriage, and rode up to her bedside. Ants in the mirror were at times replaced by an elephant’s trunk blotting out half her face. Her hair in the reflection flowed with cobwebs and the basin was matted with hair and whiskers.

Cobwebs spilled from her cereal bowl at breakfast. The bathroom floor was covered with water that vanished whenever she tried to mop it up. The carpet in the room would lift away from the floor, roll up in the form of a snake, and slither out the door. A little girl and boy with a black and white dog stood next to the bed, as did extraterrestrial-like beings with large domed-shaped heads and slitted black eyes.

Twisted heads with grotesque faces and bulbous eyes peered out from the wall, while little red carriages, trains and push bikes disappeared into it. Further history revealed an experience of ‘ant’ hallucinations 4 months previously but the images disappeared after 2 weeks. She did not seek medical advice at that time fearing that she might be considered ‘a bit odd’.

Throughout the hospital admission she was rarely free from hallucinations and would repeatedly ask for reassurance that she was ‘not going mad’. Two months after discharge the hallucinations were still intrusive. She owned a small black dog but would see several dogs resembling oversized greyhounds with unusually long snouts in her daughter’s yard.

A man and a goat, both wearing grey hats and overcoats, often stood beside her before wandering off together down a crooked road. She grew accustomed to seeing a baby seated on the lounge chair wearing grey clothes. It smiled but made no sounds. Caterpillars and tree frogs began joining her for the evening bath.

She began to notice that distractions, such as listening to the radio and attending to household chores, dampened the hallucinations, while solitude, particularly during the evening hours, tended to heighten them.

At follow-up 1 year later, she was experiencing very much the same hallucinations but was more cognisant of their unreality and less anxious as a result. The only new hallucination that had since appeared was that of a bright kaleidoscopic array which would transiently emanate from her central field of vision.

The article has another case study which is also quite spectacular, and, curiously, also features a Roman chariot.

One of the most interestingly things about Charles Bonnet syndrome is that fact that it is typically associated with the most complex hallucinations, but usually due to damage to the retina or early visual pathway.

In other words, damage to the part of the visual system which deals with the most basic aspects of vision (detecting lines, light and dark and so on) can cause the most spectacular visual distortions.

It’s not fully clear why this is, but one of the most popular theories is that visual information gathered by the initial part of the system is used to limit the interpretations made by the perceptual processes later in the stream which are focussed on working out significance and meaning.

We can see this system breaking down a bit when we see momentary ‘pictures’ in TV static or in flames, as the fuzzy input means many interpretations can be made.

However, when we’re looking at more ordered scenes, our interpretation is usually more constrained – it’s more difficult to interpret light patterns from a pencil as something else.

The theory goes that when we can’t process light patterns very successfully, owing to damage to the early visual system, the interpretation processes go wild, so hallucinations are ‘released’ and cavort unconstrained through our conscious mind.

Link to article on the neuroscience of Charles Bonnet syndrome.
Link to PubMed entry for same.

Misfortunes, Troubles, Disappointments

I’m just reading Lisa Appignanesi’s so-far excellent book Mad, Bad and Sad: A History of Women and Mind Doctors from 1800 to the Present where she reproduces an 1810 table of causes of insanity from London’s Bethlem Hospital on p54.

It was compiled by the physician William Black and lists various afflictions that have apparently caused mental illness followed by a count of the number of affected patients.

Misfortunes, Troubles, Disappointments

Grief (206)
Religion and Methodism (90)
Love (74)
Jealousy (9)
Pride (8)
Study (15)
Fright (31)
Drink and Intoxication (58)
Fevers (110)
Childbed [i.e. birth or nursing babies] (79)
Obstruction (10)
Family and Heredity (115)
Contusions and Fractures of the Skull (12)
Venereal (14)
Small Pox (7)
Ulcers and Scabs dried up (5)

Symbol of remembrance triggers mass false memory

There’s an interesting short research report in Cortex about how a national symbol adopted in Italy after the 1980 terrorist bombing of Bologna train station likely instilled a false memory about the following 16 years.

On the morning of August 2nd, 1980, at 10.25, a bomb exploded in Bologna Centrale station, killing eighty-five people wounding over 200.

The blast also stopped the large station clock on the side of the building at the moment of the explosion, freezing the hands in the 10.25 position. Shortly afterwards, the clock was repaired and it continued to function normally for 16 years.

However, when it broke in 1996, it was decided to leave the clock in its broken state and permanently set the hands at 10.25 in remembrance of the tragedy, owing to the fact that the image of the frozen clock had been widely used in commemorations during the intervening years.

A group of Italian psychologist were aware that repetition tends to cause false memories and decided to test residents of Bologna, all familiar with the station, for their memory of the clock.

What they found was that the majority of people falsely remembered that the clock had been frozen since the bombing and never worked since, despite the fact that this was never the case.

This included those who had regularly seen the clock working fine, presumably on a daily basis, owing to the fact that they worked at the station during the 16 intervening years.

Of the 173 participants who knew that the clock is now stopped, 160 (92%) stated that the clock has always been broken. 127 (79%) further claimed to have seen it always set at 10.25, including all 21 railway employees. Most interviewees did not know that the clock had been working for over 16 years and stated that it had always been broken.

From the 173 people who knew that at the time of testing the clock was stopped, a subgroup of 56 citizens who regularly take part in the annual official commemoration of the event has been further considered: only six (11%) of them correctly remember that the clock had been working in the past.

The findings are an interesting parallel to a study published last year on the London bombings. The researchers asked participants about their memories of seeing TV footage of the bus exploding in Tavistock Square.

Despite the fact that no such footage exists and no reconstruction was ever shown on TV, 40% of British participants ‘remembered’ seeing it and produce ‘details’ of the coverage when asked.

Link to study on Bologna bombings.
Link to PubMed entry for same.
Link to summary of London bombings study.

Rendered frantic, crazy by unbroken concentration

Advances in the History of Psychology has just alerted me to a fascinating short article on the work of the influential 18th-century physician Samuel Tissot, who wrote a book arguing that concentrating on books for too long damaged the mind.

The 18th century was when books were becoming cheap enough to be widely available to the middle classes and it’s interesting that this new cultural development produced a similar pseudo-medical concern about damage to the mind that we often hear today, but in a completely different direction.

While modern day technological doom-sayers suggest that technology damages the mind because it interrupts concentration, 18th century technological doom-sayers suggested that reading damaged the mind because it required too much concentration.

Neither have an evidence base, but I maintain a morbid interest in medicalised concerns about new technology and cultural innovations, which often take the same basic form but cite a cause which is always curiously in line with the authors’ prejudices.

It turns out Tissot, like many of this medical contemporaries, was also obsessed with masturbation, which he cited as the cause of madness and a host of other psychological problems.

Catholic church aside, it seems a ridiculous view to us now, but it was widely held by some of the most prominent and influential medical men of the time.

Link to Guardian ‘Beware: studying can make you ill’.
Link to AHP on ‘Read Till You‚Äôre Crazy’.

The attractions of humour

The new edition of Scientific American Mind is out an it has an excellent cover article on the psychological effects of humour and laughter.

It’s a remarkably wide-ranging article, covering everything from the effect on the immune system, to laughter’s pain killing properties to its beneficial effect on mental health.

There’s also an interesting aside on the role of humour in attraction:

In 2006 psychologists Eric R. Bressler of Westfield State College and Sigal Balshine of McMaster University in Ontario reported that women are more likely to consider a man in a photograph a desirable relationship partner if the picture is accompanied by a funny quote attributed to the man. In fact, the women preferred the funny men despite rating them, on average, less intelligent and less trustworthy.

Although the men in Bressler and Balshine’s study did not prefer witty women as partners, other research indicates that both men and women value a “sense of humor” when choosing a partner. Either way, males do seem to like ladies who laugh at their jokes. A 1990 study suggests that when women and men chat, the amount of laughing by the woman indicates both her interest in dating the man and her sexual appeal to the man. (The man’s laughter did not relate to attraction in either direction.)

The issue also has freely available online articles on ‘brain training’, the psychological effect of architecture and personality disorder with many more in the print edition.

Link to April’s SciAmMind.

On the frontiers with the neural gene mappers

Wired has an excellent article on the Allen Institute for Brain Science’s ambitious mission to map where each gene is expressed in the brain.

We tend to think of genes in terms of their ability to pass on characteristics to new generations, but the moment the egg and the sperm combine, genes start coding for proteins which the body uses to do its work.

Of course, this includes the brain, so knowing what type of genes produce proteins in which areas of the brain gives us a big clue to some of the brain’s functions.

The article is, perhaps, a little overly hopeful about the significance of a having a gene map for understanding complex mind functions or disorders (autism is mentioned as an example) – suggesting that some research hits a dead end without it.

Perhaps something useful to mention is that one of the key pieces in the puzzle of gene expression in the brain is not where genes are expressed but under what conditions they are expressed.

While your DNA has the ability to express every protein it has genes for, the cell regulates this process so it reacts to current conditions dynamically.

In other words, the genes are more of a reference book, and the cell’s other regulation processes decide how and when to use this information.

As far as we know, all learning in the brain happens through proteins, meaning that experience, learning, thought, motivation – or any other ‘psychological level’ process we can think of, acts through the many, complex and not fully understood regulation processes.

So understanding the reference book is an essential but insufficient part of the picture. The real deal is in understanding how the brain’s cellular workers use the information to mediate between genes and the processes we understand at the psychological, behavioural or experiential level.

This is part of the new science of epigenetics, and there are high hopes that this will be a big part of future neurobiology.

This doesn’t imply that we don’t need to understand the role of experience and the environment in deference to purely reductionist neurobiological models. In fact, these new developments have stressed the importance of integrating these bigger concepts.

And this is largely because we now have the beginnings of a science that could help us make links between these different levels of explanation.

Nevertheless, the Allen Brain Atlas is an important and exciting part of this new science and the Wired article is a great introduction to the project.

Link to Wired article ‘Scientists Map the Brain, Gene by Gene’.
Link to Wired image gallery of the Allen project.

Nothing but a G thing

The New York Times has an obituary for Earl Wood, the man who invented the G-suit, the pressurised suit for fighter pilots that prevents them losing consciousness when g-forces drain blood from the brain.

The problem became apparent as fighter plane technology advanced to the stage where they became so fast and manoeuvrable that pulling tight corners or sharply accelerating put huge strains on the pilots’ bodies.

The acceleration temporarily impedes the heart‚Äôs pumping power and cuts blood supply to the brain. A tight turn might cause the pilot to lose consciousness briefly, leading to a crash…

To counter a precipitous drop in blood pressure, the team designed a suit that placed air bladders at a pilot’s calves, thighs and abdomen; a valve inflated the bladders as G-forces increased. Constriction of the bladders on the arteries raised blood pressure and helped keep blood flowing to the brain. The suit’s prototype was tested successfully by Dr. Wood and others in a dive bomber on flights that involved steep descents.

At the same time, the Mayo team developed an exercise, called the M1 maneuver, in which a pilot would shout or grunt under G-force conditions. The grunting compressed arteries and tensed muscles and was at least as important as the revolutionary suit for resisting G-forces.

Link to obituary for Earl Wood, G-suit inventor.

Copyshop suicide

Photo by Flickr user just.Luc. Click for sourceBad Science has a great article on the ‘copycat suicide’ effect, where media reporting of suicide can increase the chances of suicide in other people.

Copycat suicide is sometimes called the ‘Werther Effect’, after Goethe published his 1774 novel ‘The Sorrows of Young Werther’ which depicted Werther’s suicide and was reportedly followed by people imitating the same method to end their lives.

It’s an interesting effect because it shows the influence on the media on what people usually think of the most extreme of decisions.

An excellent 2003 review article on the subject found that the effect holds for all media reports of suicides (including fictional ones) but celebrity suicide is most associated with subsequent deaths. Interestingly, it notes that the largest known increase followed the death of Marilyn Monroe.

The review also found found that the greater the coverage of the suicide, and the more details in the reporting, the larger the increase in subsequent deaths.

Because of this, there are now media guidelines for reporting suicide, and the Bad Science article reports on a particularly bad example where the journalist reported exactly the sort of thing most associated with increased risk in a single story – virtually nothing except details of the suicide method.

One of the most interesting bits of the Bad Science piece doesn’t appear in the print version. However, it discusses research that found the majority of people who attempt suicide and survive are pleased they did some years later:

There is a literature which I think is extremely powerful, and yet unanimously ignored by mainstream media, and that is the follow-up data on what happens later in life to people who have felt so suicidal that they have made serious attempts on their own lives.

In extremis Pajonk et al followed up a large number of people who they picked up in intensive care after very serious suicide attempts. Amongst those who survived, and did not have serious psychotic illnesses, six years later, the majority were happy and well, living productive family lives, and were ‚Äì we might reasonably interpolate – glad to be alive.

Link to Bad Science article on media reporting of suicide.
Link to review article on media and suicide (with open-access link).

Neurosurgeon has mid-operation heart attack, continues

BBC News is reporting that neurosurgeon Claudio Vitale had a heart-attack during an operation to remove a brain tumour, but continued with the surgery as he knew the patient wouldn’t recover if he left the theatre.

According to reports, Mr Vitale started to feel chest pains part way through the operation at Naples’ Cardarelli Hospital.

When the pains worsened, Mr Vitale’s team urged him to stop the procedure and get treatment, but he refused.

He agreed to undergo a blood test, which confirmed a heart problem, but the neurosurgeon insisted on completing the operation before getting medical help, reports say.

ABC News also has a good write-up.

Link to BBC News article ‘Doctor in mid-surgery heart scare’ (via MeFi).

Focus me

Photo by Flickr user GJ Charlett III. Click for sourceThe Journal of Sex Research has a fascinating article on the role of attention in sexual arousal and how we use our mental focus to explore and control excitement during sex.

We can see from our everyday lives that attention is important for sex. We can distract ourselves to avoid sexual arousal when our mind has wandered onto sexual topics and we don’t want to get aroused, or we want to prolong sexual enjoyment without getting over-aroused.

We also can do the reverse and focus strongly on sexual fantasises or our partner to dispel other thoughts and lose ourselves in the sexual moment.

However, the article looks at the scientific research on attention during sex and discusses how this can help us understand and treat sexual problems.

The drug industry has a lot invested in telling people that sexual difficulties are almost entirely due to problems with the genitals.

For example, the website for Viagra promotes the line that erectile dysfunction is a problem with your cock, saying that “It happens when not enough blood flows to the penis”.

Which is a bit like saying poverty is when not enough money gets to poor people. It describes the outcome but not the cause.

The article makes clear that many sexual problems can be best understood in terms of how the mind is working and many sexual problems can be equally well treated with psychological methods.

In other words, it’s often not that the genitals are ‘not working’, but that we’ve got into a situation where it’s hard to achieve the necessary level of sexual arousal because of, for example, distraction, anxiety or low self-confidence which cause a negative feedback loop that takes our focus away from making love and onto other non-arousing things.

Based on such findings, Barlow (1986) posited a model of erectile dysfunction, central to which is the idea that increased autonomic arousal results in a narrowing of attentional focus (Wiegel, Scepkowski, & Barlow, 2007). The model outlines a process whereby a male focuses his attention on either erotic cues or nonerotic, self-evaluative cues (e.g., fears over performance). In both cases, autonomic arousal (due to sexual arousal in functional men and anxiety in dysfunctional men) creates a feedback loop, further narrowing the man’s attentional focus on the information to which he is already attending.

In sexually functional men, attention becomes increasingly focused on erotic information, creating a positive feedback loop. This feedback loop facilitates sexual response and erection, which in turn leads to approach behavior. In the case of sexually dysfunctional men, attention becomes more focused on nonsexual, task-irrelevant material, creating a negative feedback loop.

In clinical psychology, many problems, particularly with anxiety, are understood as malfunctioning feedback loops, where the person’s attempt to control their anxiety actually serve to maintain it in the long-term.

Interestingly, the article touches on the use of mindfulness meditation, known to cause attention changes and anxiety reduction, in the treatment of sexual problems.

For example, some preliminary studies have been completed by psychologist Lori Brotto and colleagues with promising results.

Link to ‘The Role of Attention in Sexual Arousal’.
Link to PubMed entry for same.

2009-03-27 Spike activity

Quick links from the past week in mind and brain news:

Brain Hammer is on fire at the moment, lots of great posts on philosophy of mind.

Dodgy fMRI ‘lie detection’ evidence to be submitted as evidence in court, reports Frontal Cortex and piece from Wired. Next in court, lie detection through reading the clouds.

Alzheimer International has an awesome short promo video. In Spanish but you don’t need the language to understand it. Beautiful.

Daniel Dennett discusses the risk of robot war in a short video for Big Think.

Technology Review has an article on an exciting new technology to chart human activity, on city maps, on mobile devices, in real time.

The excellent BPS Research Digest is now on Twitter.

PsyBlog has an excellent, and beautifully illustrated, article on the ‘attention spotlight‘.

The miracle fruit, which changes our taste by interfering with tongue receptors, is discussed on CNN.

Eric Schwitzgebel has more on his compelling exploration over whether philosophical study influences real world behaviour, finding political scientists don’t go to vote differently from most other people.

A fantastic study on the genetics of white matter structure and link to IQ is discussed by NPR. Take the stuff about ‘thinking faster’ with a pinch of salt. They didn’t analyse speed of processing directly, they’re just inferring ‘speed’ from white matter integrity.

The Frontal Cortex has a great piece on male female differences, or the lack of them, in the psychology of decision-making.

Philosopher Alva Noe discusses his new book on consciousness and embodiment in an interview for Salon.

Wall Street Journal Blog reports that the Journal of the American Medical Association has created an inadequate new policy after the editors bullied a neuroanatomy professor who pointed out undeclared conflicts of interest in a paper they published. The Economist covers the fall out, patients’ group call for editors to resign.

“The medial prefrontal cortex exhibits money illusion” reports paper in the Proceedings of the National Academy of Sciences. I wondered where magicians get all those coins from.

The New York Times reports depression is linked to thinned brain cortex.

The American Psychiatric Association starts to remove the drug company teat from its mouth by halting industry-funded symposia and free lunches at its conferences – according to Medical News Today.

Where time becomes a loop

New Scientist has an excellent article on the neuroscience of deja vu, tackling how our brain can generate the anomalous feeling that we are reliving an event when it has happened for the first time.

The article tackles both experiments that try to trigger and measure deja vu in healthy participants, as well as in people who experience, sometimes permanent, deja vu because of epilepsy of brain injury.

There is one slightly awkward bit in the article however.

One possibility is that d√©j√† vu is based on a memory fragment that comes from something more subtle, such as similarity between the configuration or layout of two scenes. Say you are in the living room of a friend’s new house with the eerie feeling that you have been there before, yet knowing you can’t possibly. It could be just that the arrangement of furniture is similar to what you have seen before, suggests Cleary, so the sense of familiarity feels misplaced…

Although the familiarity idea appeals to many, Moulin, for one, is not convinced. His scepticism stems from a study of a person with epilepsy that he conducted with Akira O’Connor, now at Washington University in St Louis, Missouri. This 39-year-old man’s auras of d√©j√† vu were long-lasting enough to conduct experiments during them. The researchers reasoned that if familiarity is at the root of d√©j√† vu, they should be able to stop the experience in its tracks by distracting the man’s attention away from whatever scene he was looking at. However, when he looked away or focused on something different, his d√©j√† vu did not dissipate, and would follow his line of vision and his hearing, suggesting that real familiarity is not the key. The fact that an epilepsy aura can cause d√©j√† vu at all suggests that it is erroneous activity in a particular part of the brain that leads to misplaced feelings of familiarity, suggests Moulin.

This dichotomy is interesting because it implies that ‘brain activity’ and ‘misplaced familiarity’ are somehow separate, when we know each can just be descriptions of the same thing on different levels of interpretation.

However, it also implies that deja vu can only be caused in one particular way, when it could be caused by many different processes.

For example, think about trying to understand why someone got angry. We could be studying one person who gets angry when his football team loose, another when he is wrongly accused and another when he has a seizure in his limbic system.

You could use each one of these explanations to say that the other explanation is wrong if you believed that anger could only be caused in one way.

However, if we accept that it is an experience described at the level of psychology or behaviour there could be many ways of explaining it, and many paths that lead to the same experience, each cause does not cancel the other out.

Like deja vu and probably many other experiences, there are many causes and ways of explaining causes for the same phenomena.

Link to NewSci article ‘D√©j√† vu: Where fact meets fantasy’.

Much madness is divinest sense

I’ve just found this fantastic poem by 19th century American poet Emily Dickinson, where she discusses the link between conformity and madness.

Madness is defined partly in terms of what we consider normal and one of the great critiques of psychiatry is that it is used a method of control over those who do not conform to acting with the acceptable range of behaviour.

To what extent this is necessary or ethical for people who may not have good insight into their extreme states of mind has been one of the key debates in mental health for hundreds of years.

Dickinson describes the 19th method of control (“handled with a chain”) although I can’t say I ever seen an angry person declared sane, as we still have this implicit idea that being able to control your emotions when necessary or in your interest is a sign of sanity.

Dickinson’s poem:

Much madness is divinest sense
To a discerning eye;
Much sense the starkest madness.
’T is the majority
In this, as all, prevails.
Assent, and you are sane;
Demur, you ’re straightway dangerous,
And handled with a chain.

Dickinson is probably best known among cognitive scientists for her poem on the brain (‘Wider than the sky’), which is perhaps one of the most beautiful literary pieces on our second favourite organ, and widely quoted by researchers.

Link to Bartleby entry for ‘Much madness is divinest sense’.

Why children don’t make us happy (on average)

Photo by Flickr user carf. Click for sourceThe Psychologist has a counter-intuitive article on research that indicates, contrary to popular belief, that having children tends not to make people happier. In fact, parents reliably report that they feel less happy than in their child free days, and less happy when compared to childless couples.

Over the past few decades, social scientists like me have found consistent evidence that there is an almost zero association between having children and happiness. My analysis in the Journal of Socio-economics (Powdthavee, 2008) is a recent British example of parents and non-parents reporting the same levels of life satisfaction, on average.

But the warnings for prospective parents are even more stark than ‘it’s not going to make you happier’. Using data sets from Europe and America, numerous scholars have found some evidence that, on aggregate, parents often report statistically significantly lower levels of happiness (Alesina et al., 2004), life satisfaction (Di Tella et al., 2003), marital satisfaction (Twenge et al., 2003), and mental well-being (Clark & Oswald, 2002) compared with non-parents.

It’s an interesting article as it tackles not only why having children tends not to make us happier, but also why we think it does in cultures across the world.

Link to ‘Think having children will make you happy?’.

Full disclosure: I’m an occasional columnist and unpaid associate editor for The Psychologist.

Tonic to aphrodisiac to energy drink

Image from Wikipedia. Click for sourceThe journal Evidence-based Complementary and Alternative Medicine has an interesting open-access article about guarana, a stimulating Amazonian berry that was used by the local peoples but is now a global ingredient in energy drinks and ‘aphrodisiacs’.

It is often advertised as an ingredient in energy drinks to make them sound more ‘exotic’ or ‘natural’, but the kick is largely from caffeine, and it contains about four times as much as the coffee bean.

Indeed, the article notes that guarana seeds contain more caffeine than any other plant in the world.

Guaran√° (Paullinia cupana H.B.K., Sapindaceae) is a rainforest vine that was domesticated in the Amazon for its caffeine-rich fruits. Guaran√° has long been used as a tonic and to treat various disorders in Brazil and abroad and became a national soda in Brazil about a century ago. In the last two decades or so, guaran√° has emerged as a key ingredient in various ‘sports’ and energy drinks as well as concoctions that allegedly boost one’s libido.

For some time, guaran√°’s high caffeine content was thought to be a detriment because of health concerns about excessive intake of caffeine-rich drinks. But it is precisely this quality, and the fact that it has a mysterious name and comes from an exotic land, that has propelled guaran√° into a global beverage.

The article is fairly brief but is a great guide to this curious plant that is becoming increasingly used as a pick-me-up ingredient.

Link to full-text of article.
Link to PubMed entry for same.