Month: September 2006

The previous post on the neurological and psychological benefits of breastfeeding made me wonder if being breastfed is associated with a lower risk of developing mental illness later in life.

For example, those with cognitive impairment and vulnerability to stress are more likely to end up with a diagnosis of schizophrenia.

Perhaps, those who have greater cognitive ability and stress resilience because they were breastfed are at less of a risk of being diagnosed with a serious mental illness later in life.

There seems to be evidence to support this idea.

According to one study published last year, being breastfed is associated with a significantly decreased risk of developing schizophrenia.

One other study found no difference in risk for previously breastfed and non-breastfed adults, but found evidence that early breastfeeding pushed back the time at which those with schizophrenia developed symptoms, suggesting breast milk might postpone the onset of the condition many years later.

Science News reports on research that suggests that breastfed babies show measurable benefits in terms of action control and coordination.

The coordination of movement relies heavily on good general brain function. If you ever visit a neurologist for a neurological examination, you’ll notice the majority of tests are to do with balance, muscle tone, movement and reflexes.

Hence, the examination of these functions can give a clue to how well the brain is developing.

A research team led by Dr Amanda Sacker set out to use these sort of tests to compare how breastfed and non-breastfed babies were developing.

To the researchers’ surprise, [research collaborator] Kelly notes, children “were about 50 percent less likely to have a [developmental] delay if they had prolonged, exclusive breastfeeding when compared to those who were never breastfed.” They defined breastfeeding as prolonged when it had lasted at least 4 months. Even babies receiving mother’s milk for a short while‚Äî2 months or less‚Äîwere 30 percent less likely to have a developmental delay than those who received solely infant formula, beginning right after birth.

The same team also recently reported results from another study that suggested that breastfeeding is linked to resilience in the face of psychological stress.

Link to Science News story.

The New York Times has an article on the scientific investigation of ‘hysteria’, the condition now typically called conversion disorder, where physical symptoms such as paralysis, seizures or even blindness seem to be caused by mental disorder rather than any detectable physical problems.

The diagnosis is controversial for many reasons, not least because it is largely Freudian in origin.

Actually, Freud was not the first to investigate the disorder. The French neurologist Jean-Martin Charcot made it popular with his dramatic case demonstrations using hypnotism and especially theatrical patients.

That’s Charcot in the picture above, with a patient in a ‘hysterical fit’. This painting hung above Freud’s consulting couch, and can still be seen there in his London home, now the Freud Museum.

Freud’s contribution was to provide a popular theory of why this occurs.

He argued that physical disorder could result from inner psychological turmoil as a result of unresolved conflict. He described a case of ‘hysterical paralysis’ in one of his most famous case studies, that of ‘Anna O‘.

Notably, there was little hard evidence for his theories, and critics have argued that his explanation is just used a fig leaf to hide the fact that doctors don’t know what is actually wrong with such a patient.

However, similar cases turn up regularly in neuropsychiatry clinics, and in recent years a growing body of research has tackled the issue.

‘Psychogenic non-epileptic seizures’, where people seem to have epileptic seizures but without any detectable brain disturbance, have probably received the most research attention to date (see two previous articles on Mind Hacks).

More recently, brain scanning studies have attempted to make sense of what’s going on – with some success.

In a 1997 paper published in the journal Cognition, Dr. Halligan, of Cardiff, and John C. Marshall and their colleagues analyzed the brain function of a woman who was paralyzed on the left side of her body. First they spent large amounts of money on tests to ensure that she had no identifiable organic lesion.

When the woman tried to move her “paralyzed leg,” her primary motor cortex was not activated as it should have been; instead her right orbitofrontal and right anterior cingulate cortex, parts of the brain that have been associated with action and emotion, were activated. They reasoned that these emotional areas of the brain were responsible for suppressing movement in her paralyzed leg.

Other studies have looked at paralysis induced by hypnosis as a comparison, and interestingly found that similar brain areas are involved in some cases.

Conversion disorder is still poorly understood, but it seems as if these patients are not ‘faking it’ and may have problems that are not caused by permanent damage, but are outside their conscious control.

The New York Times article looks at some of the most recent research in this area, and charts the growing acceptance of a diagnosis which has been dismissed by some people as nonsense.

Link to NYT article ‘Is hysteria real? Brain Images Say Yes’.
Link to BMJ editorial ‘New approaches to conversion hysteria’.

The latest edition of the Canadian Journal of Psychiatry has a comprehensive review of the evidence on whether cannabis contributes to causing psychotic mental illness – the best known being schizophrenia.

It has been known for a long time that there is a link between cannabis use and psychosis, but it was not known whether cannabis contributed to the development of psychosis, or whether people with psychosis were just more likely to smoke cannabis because it helps dispell some of the unpleasant emotions and feelings associated with the condition.

There is now good evidence that cannabis can contribute to the cause of psychosis, particularly during adolescence and early adulthood.

At a population level, this effect is detectable but small.

At the individual level, the effect seems to be quite variable. Recent research has suggested that the risk of developing psychosis when using cannabis is heavily influenced by what version of the COMT gene a person has.

The main conclusions of the Canadian Journal of Psychiatry review are summarised in an editorial, but for those wanting the in-depth lowdown, the full paper is also available online.

Link to August 2006 Canadian Journal of Psychiatry.

Yesterday’s Nature contains an intriguing short report of how stimulating part of the brain during neurosurgery induced the feeling that a shadowy version of the patient’s body had appeared and was mirroring the patient’s movements.

The patient was undergoing routine neurosurgery to examine the brain, prior to more serious neurosurgery to treat otherwise untreatable epilepsy.

It is not uncommon for patients to volunteer to take part in simple neuroscience experiments during these procedures.

Patients have to be awake for part of the neurosurgery anyway because the surgeons probe the brain to make sure they avoid removing any areas essential for language, memory and so on.

The experience of feeling or seeing a double or your own body is called autoscopy or heautoscopy.

In this case, a team of researchers led by neuroscientist Shahar Arzy managed to induce this experience by stimulating an area of the brain called the left temporoparietal junction.

This is the area on the left side of the brain where the temporal lobe and parietal lobe meet (see the pink arrow in the image on the left).

This is not the first case of this kind. The Nature report is from the lab of Olaf Blanke which has reported a number of cases of this condition, either owing to brain injury, epilepsy, or induced by brain stimulation.

In a 2004 paper published in Brain, Blanke’s team reported on a number of patients who experienced this phenomenon, including one who said “I see myself lying in bed, from above, but I only see my legs” when her brain was also stimulated in the left temperoparietal junction.

In a further recent paper published in Cortex, Peter Brugger and colleagues reviewed 14 cases of ‘polyopic heautoscopy’, where patients experience multiple doubles of their own body.

(NB: This paper is available on Cortex’s website but because their site is such as mess, you can’t link to it directly and you have to use Explorer to navigate. Isn’t progress great?)

The temporoparietal junction might be significant as it is thought to process and hold representations of the body and its relationship to external space.

One interesting aspect of the Nature paper is that the patient reported that her double was unpleasant and seemed to have somewhat malign intentions:

Further stimulations (11.0 mA; n=2) were applied while the seated patient performed a naming (language-testing) task using a card held in her right hand: she again reported the presence of the sitting “person”, this time displaced behind her to her right and attempting to interfere with the execution of her task (“He wants to take the card”; “He doesn‚Äôt want me to read”).

The authors suggest they may have found evidence for the mechanism behind ‘delusions of control’ or ‘passivity symptoms’ usually linked to schizophrenia.

These are experiences or beliefs that the body and / or mind is being controlled by external forces.

However, not all patients with autoscopy report their experiences as malign, and it may be that the effect of the anaesthetics (known to induce paranoia in some), epilepsy (also linked to risk for psychosis) or the stress of the operation, may have given an unpleasant or malign twist to the experience which might not be directly linked to the disruption of the proposed brain mechanism itself.

The paper is also discussed on Nature’s news service.

Link to abstract of Nature study.
Link to Nature News write-up.
Link to full-text of 2004 Brain paper.
Link to full-text of Journal of Neuroscience paper on tempororparietal junction, body image and self .