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Gene linked to autism directs speed of human brain cell development – study

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A gene whose disfunction is linked to autism and other brain-development disorders has a critical role in the growth of healthy neurons, directing the speed at which the neurons mature, according to a new study.

The study, published this month in the Journal of Neuroscience by Scripps Research neuroscientist Gavin Rumbaugh, PhD, investigates the role of the gene SYNGAP1 in the early development of human neurones.

Changes to SYNGAP1 that inactivate the gene cause a rare autism disorder called MRD5, which also typically features intellectual disability and epilepsy. When these mutations occur spontaneously in the womb and alter one of the two copies of the gene, they cause neurodevelopmental problems.

“The SYNGAP1 gene appears to be necessary for healthy human brain development, and here we’ve found that its role, at least in part, is to set the correct pace for neurons’ maturation,” Rumbaugh says.

Only a few hundred cases of MRD5 disorder have been diagnosed, but large-scale gene studies suggest that the prevalence is likely much higher. Neuroscientists expect that by studying how rare SYNGAP1 mutations cause developmental abnormalities, they will better understand the pathways through which autism arises generally.

In the new study, Rumbaugh and his team took healthy human stem cells, induced them to turn into developing neurons, and observed their development when SYNGAP1 was excised or left intact. They found that removing SYNGAP1 caused the developing neurons to essentially mature differently.

In those lacking two functional copies of SYNGAP1, the rootlike tendrils, called dendrites, through which neurons receive input signals from other neurons, started growing earlier and became bushier, compared to the dendrites in normal neurons. Also, their connection points, or synapses, developed earlier and became stronger and more numerous.

The findings are consistent with Rumbaugh’s prior studies of SYNGAP1 loss in mouse neurons, and also appear to reflect major features of MRD5 disorder. Inherently overactive brain circuits can be a cause of epilepsy, for example. In principle, they can lead to the kinds of imbalances in circuit activity that have been linked to repetitive behaviors in autism, Rumbaugh says. Also, children with MRD5 and other autism-related disorders are sometimes easily overwhelmed by noises and other sensory signals, hinting at excessive signal strength in some sensory circuits, he adds.

“We suspect one of the reasons humans have problems when they lose function of SYNGAP1 is that their neurons mature too quickly in certain areas of the brain,” Rumbaugh says. “They wire up and cause activity too quickly, and disrupt the usual balance between excitatory and inhibitory circuits so that the brain can’t control itself properly.”

Rumbaugh communicates with many families of MRD5 patients. His next step is to continue the studies using neurons derived from these patients. His lab also will collaborate with other labs that study such neurons in three-dimensional clumps called organoids, which can reveal a wider range of features of neuronal development.

“Kids with MRD5 have loss-of-function mutations in only one copy of SYNGAP1, so our hope ultimately is to find a treatment that increases expression of the remaining good copy, restoring the net production of the SynGAP protein to normal,” Rumbaugh says. “Potentially that would be a cure if delivered early enough.”

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Smoking linked to stroke in new study 

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Guido Falcone, assistant professor of neurology at Yale School of Medicine, was the senior author of the study

Adults who smoke, or are genetically predisposed to smoking behaviours, are more likely to experience a subarachnoid haemorrhage (SAH), new research has revealed.

The study found that while smokers are at a higher risk of SAH, that rises to over 60 per cent among those with genetic variants that predispose them to smoking.

The research, published in Stroke, a journal of the American Stroke Association, establishes a link between smoking and the risk of SAH for the first time.

While it has been proven in other types of stroke, this is pioneering research in its link with SAH – a type of stroke that occurs when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and the skull.

Results of the study show:

  • the relationship between smoking and SAH risk appeared to be linear, with those who smoked half a pack to 20 packs of cigarettes a year having a 27% increased risk;
  • heavier smokers, those who smoked more than 40 packs of cigarettes a year, were nearly three times more at risk for SAH than those who did not smoke; and,
  • people who were genetically predisposed to smoking behaviours were at a 63% greater risk for SAH.

Researchers also stated that while their findings suggest a more pronounced and harmful effect of smoking in women and adults with high blood pressure, they believe larger studies are needed to confirm these results.

“Previous studies have shown that smoking is associated with higher risks of SAH, yet it has been unclear if smoking or another confounding condition such as high blood pressure was a cause of the stroke,” says senior study author Guido Falcone, assistant professor of neurology at Yale School of Medicine.

“A definitive, causal relationship between smoking and the risk of SAH has not been previously established as it has been with other types of stroke.”

During the study, researchers analysed the genetic data of 408,609 people from the UK Biobank, aged 40 to 69 at time of recruitment (2006-2010).

Incidence of SAH was collected throughout the study, with a total of 904 SAHs occurring by the end of the study.

Researchers developed a genetic risk scoring system that included genetic markers associated with risk of smoking and tracked smoking behaviour data, which was collected at the time each participant was recruited.

“Our results provide justification for future studies to focus on evaluating whether information on genetic variants leading to smoking can be used to better identify people at high risk of having one of these types of brain haemorrhages,” said lead study author Julian N. Acosta, neurologist, postdoctoral research fellow at the Yale School of Medicine.

“These targeted populations might benefit from aggressive diagnostic interventions that could lead to early identification of the aneurysms that cause this serious type of bleeding stroke.”

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New campaign to reduce stroke risk launched on Stroke Prevention Day 

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Almost nine out of ten strokes are associated with modifiable risk factors

A 12-week campaign is being launched today – Stroke Prevention Day – to help raise awareness of how the risk of stroke can be reduced. 

The campaign encourages people to make one small positive change to their lifestyle to reduce the possibility of stroke, which is the fourth highest cause of death in the UK. 

According to the Stroke Association UK, 89 per cent – almost 9 in 10 – strokes are associated with modifiable risk factors in the Western countries, including lifestyle elements that can be changed to reduce risk, such as weight, diet and blood pressure. 

New research commissioned by the charity, which is leading the campaign, has also revealed: 

  •  Only 1 in 20 (6%) UK adults think they’re at high risk of a stroke, despite the fact that the global lifetime risk of stroke from the age of 25 years onward was approximately 25% among both men and women
  • Almost half (47%) of the country don’t know that high blood pressure is a top risk factor for stroke 
  • 3 in 4 people (73%) said that they have had no information about stroke reduction recently, which rises to over 4 in 5 (85%) of over-65s, who are most at risk of having a stroke.

Blood pressure is the biggest cause of stroke, with 55 per cent of stroke patients having hypertension when they experience their stroke. Further, around 1 in 4 adults from 55 years of age will develop AFib. 

“While these numbers are concerning, they also demonstrate that with increased awareness, we can all take simple steps to reduce our risk,” says Charlie Fox, sales director of OMRON Healthcare, who are supporting the Stroke Association campaign alongside Patients Know Best. 

“As an incredibly important risk factor for stroke, having a healthy heart should be a top priority and remain front of mind.”

AFib can be asymptomatic and may not be present during a medical appointment as episodes can be occasional, which means it is often left undiagnosed. 

But given its seriousness, those who may be at risk should routinely record electrocardiogram (ECG) measurements, according to current medical guidelines. 

Through doing so at home will enable patients to become more in control of their health, with OMRON being one of the companies developing the technology to support them in doing so. 

“The public wants and needs to be more in control of its health, which is why we create products and services that are suitable for use at home as part of our Going for Zero strokes pledge,” adds Fox. 

“OMRON Complete, for example, is an upcoming, clinically validated home blood pressure monitor with a built-in ECG which can help detect AFib which we’re excited to launch in the coming months. 

“It is our hope that through this awareness programme and by equipping the public with the tools it needs, we can make having an empowered and informed lifestyle the new normal.”

People with a Patients Know Best (PKB) Personal Health Record can also log readings to get a more complete picture of their health journey. This allows them to look back with ease and share readings with clinical teams and caregivers in a safe, secure and meaningful way.

Fox concludes: “Your blood pressure provides important health insights. Monitoring it regularly alongside your ECG readings empowers you with knowledge, helps you act sooner, and can even save your life”.

More information about the campaign and how you can make your one small change can be found here: www.stroke.org.uk/PreventionDay

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What are the IDDSI Levels and why do they matter?

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Wiltshire Farm Foods takes you through the importance of the IDDSI Levels

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Dysphagia, more commonly known as swallowing difficulties, can be prevalent amongst those in neuro rehabilitation. For those in recovery, understanding how their swallowing has been affected, what solutions are available and which nutritional, delicious and above all, safe, meals they should be eating, is of paramount importance.   

When someone starts to experience dysphagia, they are most commonly seen by a speech and language therapist (SLT) and a dietitian. Together, they will create a plan for the management of dysphagia. A speech and language therapist will explain in detail the importance of texture modified food and drinks and will work with you to carefully understand the right texture modification for you. 

What is IDDSI?

This is where IDDSI can help you understand your recommended texture modified diet in more detail.  IDDSI stands for International Dysphagia Diet Standardisation Initiative. This is a committee that have developed a framework of 8 levels which provide common terminology to describe food textures and the thickness of liquids for those living with dysphagia.

The purpose of IDDSI is to create standardised terminology and descriptors for texture modified foods and liquids that can be applied and understood globally – across all cultures and age spans.

Before the introduction of IDDSI, there were national descriptors in the UK which were formed by opinion rather than international standards. Having different terminology, categories and definitions in different countries caused some instances of food being of incorrect consistency. The IDDSI framework was fully adopted by food manufacturers and healthcare settings in the UK in March 2019.

The framework consists of levels for both drinks (liquids) and foods, some of which overlap as you can see in the image above. Here is a breakdown of each category in the IDDSI FOODS framework. 

Level 3 – Liquidised/Moderately Thick

  • Can be drunk from a cup
  • Does not retain its shape
  • Can be eaten with a spoon, not a fork
  • Smooth texture with no ‘bits’

Level 4 – Pureed/Extremely Thick

  • Usually eaten with a spoon (a fork is possible)
  • Does not flow easily
  • Does not require chewing
  • Retains its shape
  • No lumps
  • Not a sticky consistency

Level 5 – Minced

  • Can be eaten with either a fork or a spoon
  • Can be scooped and shaped
  • Small lumps are visible, but are easy to squash with tongue
  • Biting is not required
  • Minimal chewing required

Level 6 – Soft & Bite-Sized

  • Can be eaten with fork or spoon
  • Can be mashed/broken down with pressure
  • Chewing is required before swallowing

How can I check my meals are made to IDDSI standards?

You can check to see whether your food is compliant with the IDDSI Framework by watching these IDDSI Food Test videos.

To discover a Softer Foods range which is IDDSI compliant and created with your patients’ needs in mind, register here for the opportunity to try some complimentary meals from Wiltshire Farm Foods.

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