There is a nice write-up of two studies at the Alzheimer’s Research Forum. The first study suggests that a better quality of sleep reduces the risk of developing Dementia of Alzheimer’s Type in people who have a gene that increases the risk of Dementia of Alzheimer’s Type. In our genome we have a lot of a genes. There can be many different versions of a gene in the population – these are known as alleles. One allele of the gene for the ApoE lipoprotein increases the risk of Dementia of Alzheimer’s Type 3-4 fold above that of people with other versions of the gene. The researchers in this study used sleep actigraphy to investigate sleep. The gold standards for investigating sleep has been an approach called overnight polysomnography which usually takes place in a sleep laboratory and includes techniques such as Electroencephalography. Actigraphy involves the use of sensors attached to the body (e.g. wrists) to detect movement and other measures. This is a relatively low cost approach and has been quickly gaining ground.
The researchers found that if people in the study had the ApoE4 allele and they had a good quality of sleep, their risk of developing Dementia of Alzheimer’s Type was increased 2-fold instead of 3-4 fold (relative to those with other alleles). The researchers also looked at the brains of people who had died and found that better sleep quality was linked to a lower density of neurofibrillary tangles. Neurofibrillary tangles are another structure found in the brains of people with Dementia of Alzheimer’s Type and are thought to play a central role in Alzheimer’s Disease.
This type of result also gives us insight into another debate – genes versus environment. A longstanding debate is whether our fate is determined by the environment or by our genes. There are various ways our environment can impact on sleep e.g. noise, stressors and so these results might show one route through which the environment might modify genetic determinism.
The other study examined in the above write-up is one which looked at sleep in mice. The ancestors of rats diverged from the ancestors of humans approximately 75 million years ago during the Cretaceous era. This means that the results might not be generalisable to humans. The researchers injected mice with traceable compounds that were taken up into the brain. They found that the compounds were removed from the brain twice as quickly in sleeping mice compared with mice that were awake. The same applied with Amyloid Beta – the precursor of the Amyloid plaques found in Dementia of Alzheimer’s Type. Furthermore the research linked the removal of these compounds with the glymphatic system. Remarkably the glymphatic system’s function has only recently been confirmed and has some similarities to the lymphatic system (the lymphatic system has many functions including acting as a transport system in the body excluding the brain).
There is an interesting MedWire News write-up of research linking two genetic pathways to Bipolar Disorder. The genes code for proteins involved in synapse formation and an enzyme. The enzyme is thought to be influenced by mood stabilisers while the synapse forming protein is associated with increased excitation of neurons.
There is an interesting MedWire News write-up of a meta-analysis in which researchers looked at cardiometabolic risk factors in people with Schizophrenia. There were 185, 606 people with Schizophrenia included in the meta-analysis and the control subjects across the studies totalled 3,900,000. The data showed that the people with Schizophrenia in this study were 4.43 times more likely to have abdominal obesity than the control subjects. Furthermore they found that the risk for Diabetes was doubled relative to the controls.
Researchers in this PLOS One study looked at the instructions for authors for Psychiatry Journals. The researchers were particularly interested in specific instructions for registration of clinical trials. On the basis of their findings the researchers commented on areas of good practice and recommended stricter enforcement of publishing data on trial registration.
Dr Stoet, Professor Keith Laws and colleagues have published a new study in BMC Psychology examining the question of whether men or women are better at multitasking. The researchers administered a real world task and a more abstract task and concluded that men and women performed similarly on the tasks. There were some exceptions with women in the study performing slightly better on a task in which they formed a strategy to look for a key. You can try the task at a link in this BBC write up.
Evolutionary Psychiatry, Evolution & Culture
There has been a lot of research published on Neanderthals recently. Neanderthals were a distinct hominin species which contribute between 2 and 5% of DNA to the modern human genome. Differences between the human and Neanderthal genomes reveal several genes that are linked to diseases and so there are various reasons why understanding Neanderthals will help us understand health and illness in humans (nevertheless there are overwhelming genetic similarities between Neanderthals and humans and the gene differences represent a tiny part of the respective genomes).
Evidence from Gibraltar suggest that this is the last home of the Neanderthals. Research by Dr Matt Pope and colleagues however suggests that the Neanderthals were living in Jersey as recently as 47, 000 years ago. A recent finding in Spain suggested that Neanderthals ate herbs based on an analysis of dental tartar and were possibly using these for medicinal purposes. In a more recent response to this Professor Chris Stringer suggests that these dental findings may have resulted from consumption of animals that in turn had consumed these herbs. This possibility relates to how the food is processed. Professor Stringer argues that these patterns of consumption are hallmarks of cold adaptation. Indeed Associate Professor John Hawks suggested that Neanderthals were using animal organs as cooking vessels similarly to the way in which Haggis is prepared. However Professor Stringer does not discount the possibility of medicinal herb use. These discussions also hold relevance to models of hunter-gatherer societies which underlie many evolutionary theories of illness.
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