NHS Choices

Ebola could reach UK, but outbreak risk is low

NHS Choices - Behind the Headlines - Tue, 07/10/2014 - 12:12

“Global threat of Ebola: From the US to China, scientists plot spread of deadly disease across the world from its West African hotbed,” reports the Mail Online. This is a terrifyingly apocalyptic-sounding headline, yet the real story about Ebola is that, while still frightening and deadly, it is still a very low risk to people in the UK.

The Ebola virus causes a serious, usually fatal, disease, for which there are no licensed treatments or vaccines.

An ongoing outbreak of Ebola virus started in the West African country of Guinea, which was first reported in December 2013. This Ebola outbreak is the largest ever observed, both geographically and in terms of the number of people affected.

A study published on September 2 2014 has modelled how the virus may spread. It found that the short-term probability of international spread outside the African region was small, but not negligible. This short-term probability covered three and six weeks, which corresponded to September 1 and 22 2014. The study found that the country outside the African region with the highest risk of importation was the UK.

The original forecasts have since been revised and will have to be further updated after a Spanish nurse contracted Ebola. This happened after she treated two Spanish missionaries, who died of the disease after being flown back from Africa. This nurse is the first person known to have contracted Ebola outside of West Africa.

 

Where did the story come from?

The study was carried out by researchers from Northeastern University, the Fred Hutchinson Cancer Research Center, and the University of Florida, all in the US, and the Institute for Scientific Interchange in Italy. It was funded by the Defense Threat Reduction Agency and MIDAS-National Institute of General Medical Sciences.

The study was published in the peer-reviewed journal PLOS Current Outbreaks on September 2 2014. This is an open access journal, which is freely available to all.

The researchers state that the results of their model may change as more information becomes available and are publishing new data, projections and analysis online.

The media has reported the results of the updated projections published on the site above. It’s worth bearing in mind that, despite the very worrying headlines and the deadliness of Ebola, the risk to anyone in the UK is very low.

 

What kind of research was this?

This was a modelling study that aimed to forecast the local transmission of the Ebola virus in West Africa, and the probability of international spread if the containment measures are not successful at stopping the outbreak.

Like the weather forecast, modelling studies have to contain assumptions and approximations, and although they are useful tools to help predict what might happen, they are not always correct. The assumptions and approximations in this model are being updated by the researchers as new information becomes available.

 

What did the research involve?

The researchers used computer simulations to model the transmission of the Ebola virus.

 

What were the basic results?

The researchers estimate that each case of Ebola in West Africa will spread to 1.5 to 2 unaffected people.

In the short term (three and six weeks, which corresponded to until September 1 and September 22 2014), the probability of international spread outside the African region is small, but not negligible. The country outside the African region with the highest risk of importation in the short term is the UK.

The outbreak is more likely to spread to other African countries, which will increase the risk of international spread over a longer time period.

 

How did the researchers interpret the results?

The researchers conclude that their modelling has shown that, “the risk of international spread of the Ebola virus is still moderate for most countries. The current analysis, however, shows that if the outbreak is not contained, the probability of international spread is going to increase consistently, especially if other countries are affected and are not able to contain the epidemic”.

They go on to stress that the current model contains assumptions and approximations that may need to be modified as more information becomes available.

 

Conclusion

This modelling study found that the short-term probability of international spread outside the African region is small, but not negligible. The country outside the African region with the highest risk of importation is the UK.

The assumptions and approximations in this model are being updated by the researchers as new information becomes available, and these forecasts have since been revised.

If you are travelling abroad and are worried about infectious diseases, you may want to check out the country-by-country guide provided by the National Travel Health Network and Centre.

Health professionals should stay abreast of the latest Ebola advice from Public Health England.

 

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Global threat of Ebola: From the US to China, scientists plot spread of deadly disease across the world from its West African hotbed. Mail Online, October 5 2014

Ebola outbreak: Virus could reach UK and France by the end of the month, scientists claim. The Independent, October 5 2014

Ebola outbreak: Britain has 50% chance of importing deadly virus with the next three weeks. Daily Mirror, October 5 2014

Deadly Ebola virus could reach Britain in THREE WEEKS say scientists. Daily Express, October 6 2014

Links To Science

Gomes MFC, et al. Assessing the International Spreading Risk Associated with the 2014 West African Ebola Outbreak. PLOS Current Outbreaks. September 2 2014.

Categories: NHS Choices

Cannabis labelled 'harmful and as addictive as heroin'

NHS Choices - Behind the Headlines - Tue, 07/10/2014 - 11:29

"Cannabis: the terrible truth," is today's Daily Mail front page splash story. The paper cites the risks posed by cannabis – including a doubling of the risk of schizophrenia – based on research the paper says has "demolished the argument that the drug is safe".

The "terrible truth" is we still don't know enough about the safety and harms of cannabis because it's legally and ethically a difficult area to research. However, we can be pretty certain you can't take a fatal overdose from recreational cannabis use.

The headlines in the Mail and several other papers were prompted by the publication of a narrative review of cannabis research by Professor Wayne Hall, an expert adviser on addiction to the World Health Organization.

Professor Hall concludes that cannabis research since 1993 has shown its use is associated with several adverse health effects, including a doubling of the risk of crashing if driving while "cannabis impaired". He also found that around one in 10 regular cannabis users develop dependence.

He also reports regular cannabis use in adolescence was strongly linked with using other illicit drugs, as well as increased risk of cognitive impairment and psychoses.

In addition, cannabis smoking probably increases cardiovascular risk in middle-aged adults with pre-existing heart disease, but its effects on respiratory function and respiratory cancer remain unclear as most cannabis smokers have smoked, or still smoke, tobacco.

But as this review was not systematic, it is impossible to tell if all relevant studies have been included. And all these conclusions were based on the results of observational studies, which means we can't tell if cannabis caused all the effects.

 

Where did the story come from?

The study was carried out by a single researcher from the University of Queensland Centre for Youth Substance Abuse Research, the University of Queensland Centre for Clinical Research, and the National Drug and Alcohol Research Centre in Australia, and the National Addiction Centre at King's College London.

It was funded by the National Health and Medical Research Council of Australia and was published in the peer-reviewed journal, Addiction.

Despite the somewhat hyped headlines, the media coverage of this study was generally accurate, but did not point out the limitations of the research. Indeed, the Mail's description of the study as "definitive" is rather at odds with the nature of the research.

 

What kind of research was this?

This was a narrative review that aimed to examine the changes in the available evidence on the adverse health effects of cannabis since 1993.

It was not clear how the author identified the studies used as a basis for the review. It may be the case there are other studies showing no effect or harm that have not been included in the review.

It is also not clear how the author compiled the results of the research to come up with strengths of effect.

A systematic review is required to assess the adverse health effects of cannabis use.

Also, although the author applied rules to the interpretation of the research, the conclusions are based on the results of observational studies.

It is difficult to conclude from these types of studies that cannabis causes the effects seen, as there are still potentially differences between people who use cannabis and people who don't that could explain the differences seen.

 

What did the research involve?

The author looked at studies published over a 20-year period since 1993 (when a previous review was conducted) to see if there was evidence that cannabis caused adverse health effects. To do this, Professor Hall looked at whether:

  • there were case control and cohort studies that showed an association between cannabis use and a health outcome
  • cannabis use preceded (started before) the outcome
  • the association remained after controlling for potential confounding variables
  • there was clinical and experimental evidence that supported the biological plausibility of a causal relationship

 

What were the basic results?

The author listed the conclusions that he believes can now reasonably be drawn in the light of evidence that has accrued over the past 20 years.

Adverse effects of acute use

Professor Hall concluded that:

  • The risk of a fatal overdose is considered to be extremely small. The estimated fatal dose in humans is between 15 and 70g, far greater than it is reported a heavy user could ever use in one day. There have also been no reports of fatal overdose in the literature.
  • Driving while cannabis impaired approximately doubles car crash risk.
  • Maternal cannabis use during pregnancy modestly reduces birthweight.
Adverse effects of chronic use

Professor Hall concluded that:

  • Around one in 10 regular cannabis users develop dependence, and this rises to one in six among people who start in adolescence.
  • Regular (daily or near daily) cannabis use in adolescence approximately doubles the risks of early school leaving and cognitive impairment and psychoses in adulthood.
  • Regular cannabis use in adolescence is also associated strongly with the use of other illicit drugs.
  • Cannabis smoking may increase the risk of cardiovascular events such as angina or heart attack in middle-aged and older adults with pre-existing cardiovascular disease. Some isolated reports suggest younger people not yet diagnosed with cardiovascular disease may also be at risk of cardiovascular events.
  • The effects of cannabis on respiratory function and respiratory cancer remain unclear because most cannabis smokers have smoked, or still smoke, tobacco.

 

How did the researcher interpret the results?

Professor Hall concluded that: "The epidemiological literature in the past 20 years shows that cannabis use increases the risk of accidents and can produce dependence, and that there are consistent associations between regular cannabis use and poor psychosocial outcomes and mental health in adulthood."

 

Conclusion

This narrative review has concluded that cannabis research in the past 20 years has shown that cannabis use is associated with a number of adverse health effects.

It also found driving while cannabis impaired approximately doubles car crash risk and around one in 10 regular cannabis users develop dependence.

Regular cannabis use in adolescence approximately doubles the risks of early school leaving and cognitive impairment and psychoses in adulthood, according to the review.

Regular cannabis use in adolescence is also associated strongly with the use of other illicit drugs.

In addition, cannabis use probably increases cardiovascular risk in middle-aged adults with pre-existing heart disease, but its effects on respiratory function and respiratory cancer remains unclear because most cannabis smokers have smoked, or still smoke, tobacco.

However, as this was not a systematic review it is impossible for readers to know whether all relevant studies have been included.

All the review's conclusions were based on the results of observational studies. So while it seems probable that cannabis use increases the risk of some adverse outcomes, it is also possible there are differences between cannabis smokers and non-smokers that explain some of the differences seen.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Cannabis as addictive as heroin, major new study finds. The Daily Telegraph, October 7 2014

Cannabis can damage you, warns study. The Times, October 7 2014

The terrible truth about cannabis: Expert's devastating 20-year study finally demolishes claims that smoking pot is harmless. Daily Mail, October 7 2014

Links To Science

Hall W. What has research over the past two decades revealed about the adverse health effects of recreational cannabis use? Addiction. Published online October 7 2014

Categories: NHS Choices

Eating with a fat friend 'makes you eat more'

NHS Choices - Behind the Headlines - Mon, 06/10/2014 - 13:00

“Sitting next to overweight people makes you more likely to gorge on unhealthy food,” the Daily Express reports.

The paper reports on a small-scale research experiment showing that the presence of an overweight woman (an actress in a fat suit) near a buffet made student volunteers choose and eat a larger amount of unhealthy food (spaghetti) than when she was a healthy weight (without the fat suit). This effect was not influenced by whether the actress chose to eat healthily or unhealthily herself, something the study also looked at.

The researchers’ explanation of this was, “that when eating with or near an overweight person, you may be less likely to adhere to your own health goals.”

The study was not wholly convincing and does not prove this phenomenon exists in the general population, where food and social interactions may be more complex and nuanced. Food choice was artificially restricted to just two foods: spaghetti and salad – not the best buffet going. The same results may not have been found if participants were given a more realistic range of food choices.

It is difficult to see what practical implications the study "brings to the table", other than to be conscious of your own food choices, regardless of the social situation.

This may be a poignant reminder to those looking to maintain a healthy weight that when it comes to “all-you-can-eat” situations, it’s probably best to regard it as a special offer, not a personal challenge.

 

Where did the story come from?

The study was carried out by researchers from Southern Illinois University and Cornell University (US). No funding source was mentioned in the publication. The study was published in the peer-reviewed science journal Appetite.

The Express generally covered the story accurately, though the headlines indulged in a bit of “fat shaming”, as eating a small extra amount of spaghetti was morphed into “greed”.

 

What kind of research was this?

This was a randomised, single blind, human study looking at the influence of an overweight eating companion on healthy and unhealthy eating behaviour.

The researchers indicated that many social factors influence food intake, such as the presence or absence of eating companions, as well as the body type of these companions.

This study aimed to investigate the effect of:

  • the presence of an overweight person on what other people chose to eat
  • whether this was influenced by what food (healthy vs. unhealthy) the overweight person served themselves

 

What did the research involve?

The research team recruited 82 undergraduate college students (average age 19.5 years; 40 women and 42 men) to eat a buffet meal restricted to spaghetti with meat sauce and or salad at lunch. They also enlisted an actress to wear a suit that added three-and-a-half stone (50 pounds) to her weight. Without the “fat suit” she was a healthy weight, but donning the fat suit put her at the border of overweight/obese categories (with a BMI of 29.3).

Each of the 82 participants was randomly assigned to one of four scenarios:

  • the actress served herself healthily (more salad and less pasta) while wearing the fat suit
  • she served herself the same healthy meal without the fat suit
  • she served herself less healthily (more pasta and less salad) while wearing the fat suit
  • she served herself the same less healthy meal without the fat suit

Participants in each scenario viewed the actress serving herself and then served themselves pasta and salad.

The actress was not known to the participants, but drew attention to what she was eating by asking out loud “do I need to use separate plates for pasta and salad?” and dropping her fork and asking for a new one. She also sat in full view of the buffet queue.

The first part of the study looked at the effect of the fat suit. The second part of the study looked at the influence on the participants’ food choice when the actress served herself either a small amount of pasta and a large amount of salad (described as the “healthy eating condition”), or a large amount of pasta and a small amount of salad (“unhealthy eating condition”).

Participants were asked to report the number of hours and minutes since they had last eaten, to control for their hunger prior to the experiment.

The participants knew that the study aimed to examine eating behaviour, including serving size and intake, but they were blinded to the scenario allocation of the actress. When asked, no participants revealed suspicion about the purpose of the study.

 

What were the basic results?

These were two main findings:

  • When the actress wore the fat suit, appearing overweight, the other participants served and ate more pasta regardless of whether she served herself mostly pasta or mostly salad, compared to when she was of normal weight.
  • When she wore the fat suit and served herself more salad, the other participants actually served and ate less salad.

This meant that, regardless of whether the actress served healthy or unhealthy food, participants served and ate a larger amount of pasta (unhealthy food) when she appeared overweight than when she appeared a healthy weight.

 

How did the researchers interpret the results?

The research team said their results “support the ‘lower health commitment’ hypothesis, which predicted that participants would serve and eat a larger amount of pasta when eating with an overweight person, probably because the health commitment goal was less activated.” They added that their, “results did not support the ‘avoiding stigma’ hypothesis, which predicted that participants would serve and eat a smaller amount of pasta when an overweight confederate served herself unhealthily, to avoid association with the stigmatised group”.

 

Conclusion

This small-scale research experiment found that the presence of an overweight woman (an actress in a fat suit) near a buffet made student volunteers choose a larger amount of unhealthy food than when she was a healthy weight (without the suit). This effect was not influenced by whether the actress chose to eat healthily or unhealthily herself.

These findings suggest that people may serve and eat larger portions of unhealthy foods and smaller portions of healthy foods when eating with or near an overweight person. The researchers did not test out any reasons for this, but speculated this might be, “because they are less in tune with their own health goals”. They said this phenomenon might be easy to avoid by “assessing your level of hunger before going to the restaurant and planning your meal accordingly”.

However, the study was not wholly convincing and doesn’t prove this phenomenon exists in the general population, where food and social interactions may be more complex. For example, the study was restricted to a relatively small amount of young American adults (average age of 19.5), which may not be representative of findings in older people, children or other countries and cultures.

Similarly, the study investigated a single eating scenario, a buffet, where food choice was artificially restricted to only two foods to help the study design. The same results may not have been found in other eating scenarios, or if participants were given a more realistic range of food choices at a buffet. In addition, they did not measure how much cheese or salad dressing was used, which could have a substantial impact on whether the meal was healthy or unhealthy.

The study participants were also aware that their serving and intake levels were being recorded, which may have influenced the results.

Anyone who has been to an all-you-can-eat buffet and over-indulged can probably recognise how the social context of a meal can influence the amount of food people eat. This study suggests a further influence, body type, may also be influential, but only tentatively. This phenomenon is likely to be the subject of future research. 

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Having fat friends makes you greedy. Daily Express, October 4 2014

Fat friends DO make you eat more: Study finds we're more likely to ditch healthy eating when dining with overweight people. Mail Online, September 22 2014

Links To Science

Shimizu M, Johnson K, Wansink B. In good company. The effect of an eating companion's appearance on food intake. Appetite. Published online September 16 2014

Categories: NHS Choices

Green tea compound may improve cancer drugs

NHS Choices - Behind the Headlines - Mon, 06/10/2014 - 12:30

"Green tea could helps [sic] scientists develop new cancer fighting drugs," the Mail Online reports. But before you rush out to the shops, in no way does this study suggest green tea can fight cancer.

Instead, research has found a compound in green tea – the catchily named Epigallocatechin-3-O-gallate (EGCG) – may help improve the effectiveness of anti-cancer drugs such as Herceptin, used in the treatment of breast and stomach cancer.

This study used nanotechnology techniques to develop a new way of packaging and carrying protein drugs by combining them with EGCG.

Scientists formed a complex compound consisting of by-products of EGCG and the protein cancer drug Herceptin.

Tests in the laboratory and mice indicated the compound might have better anti-cancer properties than standard Herceptin treatment.

This is encouraging research and may lead to improvements in delivery mechanisms for protein drugs further down the line. However, it is at a very early stage of development, so new treatments are not guaranteed.

The results from the laboratory and mice studies need to be confirmed by other research groups before the team can consider testing potential treatments in humans.

Only then will they be able to assess whether such a drug delivery system could benefit people and in what circumstances. These studies will have to pay special attention to potential side effects of the drugs.

Overall, this new nanotechnology might prove useful in several years' time, but its immediate impact is minimal.

 

Where did the story come from?

The study was led by researchers from the Institute of Bioengineering and Nanotechnology, Singapore, and Beth Israel Deaconess Medical Center and Harvard Medical School in the US.

It was funded by the Institute of Bioengineering and Nanotechnology and the US National Institutes of Health.

The study was published in the peer-reviewed journal, Nature Nanotechnology.

The Mail Online's coverage was broadly accurate.

 

What kind of research was this?

This laboratory-based bioengineering study developed new drug carrier technology that was then tested in mice.

Most drugs require carrier substances to ensure the active drug ingredients reach the appropriate part of the body and are released at the appropriate time.

Carriers are usually inert and are broken down in the body over time. But high quantities of some carriers can produce toxicity in the body, leading to troublesome side effects.

This study aimed to improve current drug carriers by developing a carrier that was easily metabolised in the body, and may even do some good by itself.

The researchers said green tea extract was used because previous research indicated it had anti-cancer effects, as well as protective effects on the nervous system and DNA.

Many new technologies are tested in mice first as – despite the difference in size – they have a similar biology to humans. However, some things work differently in mice and men, so any positive findings in mice would not automatically apply to humans.

 

What did the research involve?

The research involved developing a new biological compound to carry cancer drugs based on derivatives (by-products) of one of the main ingredients in green tea, called Epigallocatechin-3-O-gallate (EGCG).

The research team joined EGCG derivatives with various anti-cancer proteins to form what are known as nanocomplexes – intricately engineered combinations of proteins.

One of the nanocomplexes comprised the anti-cancer protein Herceptin bundled with an EGCG derivative, forming a core, and a separate EGCG-derived shell around the outside.

They injected this into mice with cancer to see if the Herceptin-EGCG carrier nanocomplex was more or less effective at fighting tumour cells than "free" Herceptin alone.

 

What were the basic results?

The team found they were able to make stable nanocomplexes incorporating anti-cancer proteins with EGCG derivatives.

When the Herceptin-EGCG complex was injected into mice with cancer, it was better at targeting tumour cells (it had better "selectivity") and reducing their growth, and lasted longer in the blood than free Herceptin.

This complex also displayed better anti-cancer properties when tested on human breast cancer cells in the laboratory.

The researchers also coupled ECGC derivatives with another protein called interferon α-2a, which is used in combination with chemotherapy and radiation as a cancer treatment. This nanocomplex was better at limiting cancer cell growth than free interferon α-2a.

 

How did the researchers interpret the results?

The researchers stated they developed and characterised a new green tea-based mechanism for protein drug delivery where the carrier itself displays anti-cancer effects.

They said the nanocomplex effectively protected the protein drugs against many obstacles from the point of administration to the required delivery sites.

They concluded that, "The combined therapeutic effects of the green tea-based carrier and the protein drug showed greater anti-cancer effect than the free protein."

 

Conclusion

This study developed a new way of packaging and carrying protein drugs by combining them with a green tea extract called Epigallocatechin-3-O-gallate (EGCG), which itself may have anti-cancer properties.

They formed a complex between derivatives of EGCG and the protein cancer drug Herceptin. Tests in the laboratory and in mice indicated it might have better anti-cancer properties than non-complexed free Herceptin.

This is encouraging research and may lead to improvements in delivery mechanisms for protein drugs further down the line.

But this research remains at a very early stage of development. The results from the laboratory and mice studies need to be confirmed by other research groups before the team can consider testing potential treatments in humans.

Only then will they be able to assess whether such a drug delivery system could benefit people. These further studies will have to pay special attention to potential side effects of the drugs.

Green tea extracts are often the subject of news headlines, often in the very early stages of drug development.

Other claims made about green tea include how it can help prevent prostate cancer, reduce stroke riskboost the ability of the brain, and help ward off Alzheimer's disease.

Some people have even gone as far as claiming the beverage is a “"superfood". Many of these claims are not backed by robust evidence, however.

Overall, this new nanotechnology might prove useful in many years' time, but its immediate impact is minimal.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Green tea could helps scientists develop new cancer fighting drugs. Daily Mail, October 5 2014

Links To Science

Chung JE, Tan S, Gao SJ, et al. Self-assembled micellar nanocomplexes comprising green tea catechin derivatives and protein drugs for cancer therapy. Nature Nanotechnology. Published online October 5 2014

Categories: NHS Choices

Pages