Lithium levels in drinking water linked to fewer suicides

Photo by Flickr user Today is a good day. Click for sourceHigher levels of naturally occurring lithium in the water supply are associated with fewer suicides in the local population, reports a study just published in The British Journal of Psychiatry.

Lithium is one of the fundamental elements, but is also used by psychiatrists as one the most effective drug treatment for mood disorders, in the form of lithium carbonate and lithium citrate, where it is also known to reduce the risk of suicide.

This new study suggests that even trace amounts might have an influence on the whole population level, and this is not the first time this link has been made.

A 1990 study found higher levels of lithium in drinking water were linked to fewer incidences of crimes, suicides, and arrests related to drug addictions.

This leads to the intriguing question of whether lithium should be added to the water supply as a public health measure.

The idea of adding psychoactive substances to the water supply sounds creepy, but some might argue that if we add fluoride simply to prevent tooth decay, boosting lithium concentrations to the high end of naturally occurring levels to reduce deaths could be justified.

Philosophers and conspiracy theorists start your engines.

Link to BJP lithium study.
Link to DOI entry for same.

Extreme altitude climbs and the Sherpa brain

It’s now well known that high altitude mountain climbing damages the brain and causes a marked reduction in mental functioning.

I naively assumed this was true for everyone but I just found an intriguing 1996 study that compared brain function of lowland mountain climbers and Nepalese Sherpas after ascent to high altitude, which found that the Sherpas suffer few of these neurological problems.

Are Himalayan Sherpas better protected against brain damage associated with extreme altitude climbs?

Garrido E, Segura R, Capdevila A, Pujol J, Javierre C, Ventura JL.

Clin Sci (Lond). 1996 Jan;90(1):81-5.

1. The potential risk of brain damage when low-landers attempt to climb the highest summits is a well-known fact. However, very little is known about what occurs to Himalayan natives, perfectly adapted to high altitude, when performing the same type of activity.

2. Taking into account their long-life climbing experience at extreme altitudes, we examined seven of the most recognized Sherpas with the aim of performing a comprehensive neurological evaluation based on medical history, physical examination and magnetic resonance brain imaging. We compared them with one group of 21 lowland elite climbers who had ascended to altitudes of over 8000 m, and another control group of 21 healthy individuals who had never been exposed to high altitude.

3. While all of the lowland climbers presented psychoneurological symptoms during or after the expeditions, and 13 of them (61%) showed magnetic resonance abnormalities (signs of mild cortical atrophy and/or periventricular high-intensity signal areas in the white matter), only one Sherpa (14%) showed similar changes in the scans, presenting neurological symptoms at extreme altitude. The neurological examination was normal in all three groups, and no neuroimaging abnormalities were detected in the control group.

4. The significant differences, in both clinical and neuroimaging terms, suggest that Sherpa highlanders have better brain protection when exposed to extreme altitude. Although the key to protection against cerebral hypoxia cannot be established, it is possible that an increase in the usually short period of acclimatization could minimize brain damage in those low-landers who attempt the highest summits without supplementary oxygen.

Link to study of neurology of lowland climbers and Sherpas.

NeuroPod oscilates 100 year-old autistic robots

The latest edition of Nature’s excellent neuroscience podcast NeuroPod has just the wires and discusses using light to control the brain, a quite remarkable breakthrough in the genetics of autism, emotional robots and neurologist Rita Levi-Montalcini, the first Nobel prizewinner to turn 100.

The highlight is probably the section about Rita Levi-Montalcini who jointly won the Nobel prize for her discovery of nerve growth factor, a protein that is known to be key in neuroplasticity.

Although actually, it’s one of the most interesting and varied NeuroPod’s I’ve heard in a while, which is saying something for a programme which is usually on top form. Enjoy.

Link to NeuroPod page with streaming and download.
mp3 of April edition.

Blast from the past

New Scientist covers the debate on the causes of the non-specific emotional and cognitive symptoms that are appearing at an alarming rate in US soldiers who have been caught up in blasts while on service.

The controversy centres on whether the symptoms of ‘post concussional syndrome’ (which can include depression, irritability, concentration difficulties, headaches and reduced memory function) are caused by damage to the brain or from shock waves of the explosion, or are largely triggered by an emotional reaction to the stress of war.

It’s an interesting debate, not least because it’s almost 100 years since almost exactly the same debate raged over shell shock.

This is from an excellent article by medical historian Edgar Jones and colleagues who discuss the similarities between the ‘shell shock’ debates, and the current controversy:

Frederick Mott, then Britain‚Äôs leading neuropathologist, who was recruited by the War Office to discover the etiology of the disorder, argued that in extreme cases shell shock could be fatal if intense commotion affected “the delicate colloidal structures of the living tissues of the brain and spinal cord,” arresting “the functions of the vital centers in the medulla”. It was also speculated that the disorder resulted from damage to the CNS from carbon monoxide released by the partial detonation of a shell or mortar. In other words, shell shock was formulated as an organic problem even though the pathology remained unclear.

However, research conducted in 1915 and 1916 by Myers, consultant psychologist to the British Expeditionary Force, led to a new hypothesis. Based on his own observations, an increasing appreciation of the stress of trench warfare, and the finding that many shell-shocked soldiers had been nowhere near an explosion but had identical symptoms to those who had, Myers suggested a psychological explanation. For these cases, the term “emotional,” rather than “commotional,” shock was proposed. The psychological explanation gained ground over the neurological in part because it offered the British Army an opportunity to return shell-shocked soldiers to active duty.

As mentioned by the NewSci two big studies have recently found strikingly similar results: many soldier who have the symptoms of ‘post concussional syndrome’ were never actually in an explosion.

Extreme stress and trauma, of whatever type, seems to predict the likelihood of someone having the symptoms better than actually being caught up in an explosion.

The more things change, the more they stay the same.

Link to NewSci ‘Brain shock: The new Gulf War syndrome’.
Link to ‘Shell Shock and Mild Traumatic Brain Injury: A Historical Review’.

Voodoo II: this time it isn’t personal

More analysis problems with brain scanning research have come to light in a new study just released in Nature Neuroscience and expertly covered by the BPS Research Digest. It demonstrates that the common practice of using the same data set to identify an area of interest and then home in on this area to test further ideas can lead to misleading results.

This usually occurs when brain activation is compared between two conditions where participants are doing different tasks. A whole brain analysis looks for statistically significant differences at every point in the brain.

It’s very complete, but because of the large amount of data, but the data also contains a large amount of noise, so it’s hard to find areas which you can confidently say are more active in one condition than the other.

An alternative approach is to only look at activation in one area of the brain, perhaps an area where it is most likely to occur based on what we already know about how the brain works. This is called region of interest analysis (often done with the wonderfully named ‘MarsBaR‘ tool) and because the data set is much smaller, it is more likely to find a reliable difference.

However, some studies do a whole brain analysis to find likely areas, and then home in using region of analysis tools to examine them ‘more closely’. This ‘magnifying glass’ metaphor seems intuitive, but because your using the same data set to create and test hypothesis, it can be problematic.

It’s like shooting arrows randomly into a wall and then drawing a target around ones which landed together. Someone looking at wall afterwards might think the archer was a good shot, but this impression is caused by the after-the-event painting of the target, and the same problem could affect these brain imaging studies.

After the recent furore over the ‘voodoo correlations’ study, this new study is markedly more measured in its language and doesn’t list individual offenders.

Indeed, the ‘Voodoo Correlations in Social Neuroscience’ paper was actually retitled on publication to ‘Puzzlingly high correlations in fMRI studies of emotion, personality, and social cognition’, presumably to avoid stirring the pot any further.

However, this new study takes a similar tack, demonstrating through several careful simulations that ‘double dipping’ a data set is likely to distort the results just due to statistical problems.

From the BPS Research Digest:

Nikolaus Kriegeskorte and colleagues analysed all the fMRI studies published in Nature, Science, Nature Neuroscience, Neuron and Journal of Neuroscience, in 2008, and found that 42 per cent of these 134 papers were guilty of performing at least one non-independent selective analysis – what Kriegeskorte’s team dub “double dipping”.

This is the procedure, also condemned by the Voodoo paper, in which researchers first perform an all-over analysis to find a brain region(s) that responds to the condition of interest, before going on to test their hypothesis on data collected in just that brain region. The cardinal sin is that the same data are used in both stages.

A similarly flawed approach can be seen in brain imaging studies that claim to be able to discern a presented stimulus from patterns of activity recorded in a given brain area. These are the kind of studies that lead to “mind reading” headlines in the popular press. In this case, the alleged statistical crime is to use the same data for the training phase of pattern extraction and the subsequent hypothesis testing phase.

Link to BPS Research Digest on the fMRI analysis problems.
Link to PubMed entry for study.

Stylish psychotherapy magazine launches

Contemporary Psychotherapy is a new magazine dedicated to the practice of psychological treatment of all types and the current debates in this sometimes hotly contested field.

The first issue contains articles on the future of psychotherapy, CBT in North America, how psychiatrists deal with somatic or psychogenic symptoms and the challenges in conducting psychotherapy with asylum seekers, to name but a few.

It makes a good complement to the US-based Psychotherapy Networker magazine, it’s stylishly put together, you can download it for free as a PDF file, and long may it continue as it’s off to a brilliant start.

Link to Contemporary Psychotherapy with PDF download.

Encephalon 68, 69 and my memory is like a sieve

The 69th edition of the Encephalon psychology and neuroscience carnival has just appeared on Brain Stimulant and… dear God, I just realise I missed the 68th edition on the excellent Ouroboros as well, so here are both for your reading pleasure.

A couple of my favourites include a fantastic post on Neuroanthropology post entitled “Who you callin‚Äô a ‚Äòneuroconstructivist‚Äô punk?!” (actually, I added the punk, but you get the idea), and a Neurocritic article on a curious neurological condition where people lose the ability to correctly point at a named body part.

I always say there’s plenty more, but this time there’s a whole load more where that came from, thanks to my slightly faulty memory.

Link to Encephalon 68.
Link to Encephalon 69.