Another year has whizzed by, and the time is here again to take a look back over the past 12 months in medicine. This time last year, the success of the Ice Bucket Challenge and the horrors of the Ebola outbreak stood out for the end-of-year review, but what among the hundreds of developments deserves special mention this year?

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Prominent medical news stories in 2015 have featured Alzheimer's disease, autism, "female Viagra" and the possibility of head transplants.

Well, there was one Internet phenomenon that called for answers from medical science - that of "the dress" - and tropical disease was certainly newsworthy again in 2015.

But what really broke through in medicine this year?

Below is a list of just some of the areas of medicine that have seen interesting developments over the course of 2015.

Jump to selected topics highlighted here (or scroll through the article for the full list of topics in alphabetical order):

Head-turning medical news

Whatever your area of interest, one set of headlines was particularly striking in 2015, centering on developments that for the first time brought into the realm of reality the incredible idea of a complete head transplant.

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Could 2016 witness the world's first head transplant following developments that occurred this year?

Dr. Sergio Canavero first tantalized the world with the prospect back in February, saying it could be possible to overcome the last remaining challenges of reconnecting the severed spinal cord and preventing total immune rejection of the new head - small obstacles, naturally.

In October, Dr. Canavero confidently stated that the first human head transplant "will be a success," and this news was quickly followed by a 30-year-old Russian volunteering for the procedure.

Now, "head transplant" is the correct description if you take the view of the body accepting a new head - immunologically speaking it is the body, not the head, that decides whether to accept or reject.

A better description may be "body transplant" - for the medical reality in question concerns people whose heads are trapped with their completely disabled bodies, and who would opt to have their head transplanted onto a new, healthy (but deceased) donated body.

Could 2016 possibly be the year that a human head transplant actually takes place? And if it could, would the headlines about head or body transplants worry us in terms of the decisions over who of those among us could, or could not, be considered eligible?

Groundbreaking medical news

The test of whether or not a news story in medicine truly relates to a groundbreaking development cannot usually be applied in full until after a number of years.

To find out, ask whether there has there been a change to clinical practice. Has the development changed the way that health and disease are managed in the everyday medical setting?

These are the developments that overturn scientific understanding or change medical practice and, therefore, find their way into MNT's updates, to one of the Knowledge Center topics.

We hope you enjoy the rest of this overview for the past year's medical headlines, and it comes with all our best wishes for the holidays and the new year ahead.

Antibiotics

The surgeon general has warned that around 2 million people are estimated to develop infections with antibiotic-resistant pathogens each year in the US.

It is a problem that England's counterpart - its chief medical officer - has been warning will result in minor and routine surgical operations becoming high-risk procedures. But research is making some strides against the issue:

Autism

Medical research has been driven for years to reach a full understanding of what causes autism or autism spectrum disorder (ASD), during which time there has been controversy about various factors becoming linked to the spectrum of disorders.

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New studies have added to the growing body of research linking genetics with autism spectrum disorder.

One area that has shown consistency, though, is genetic risk, and adding to the body of science in 2015 were two studies:

  • How a gene mutation can cause autism - knowing that genetic studies have been linking about 1,000 genes to autism, one group of scientists published details in August of exactly how mutating one of these genes can lead to the disorder
  • New study identifies epigenetic signatures - this research mapped some genetic patterns in paternal DNA that could be linked to autism in offspring. The scientists publishing in April already knew there was a higher genetic risk in the children studied because they had an older sibling from the same father already diagnosed with autism.

On the same news day of the latter study, a separate paper was published that had investigated diagnostic delays in autism. This was news that children with ASD were not diagnosed on average until 5 years of age - almost 3 years after parents in the study voiced concerns to health care professionals.

There was good news in ASD diagnostics and care, however, with claims of an "autism discovery." Brain imaging revealed language development differences that could predict those 1-year-olds who would develop along the autism spectrum with poor language abilities versus those who would develop good communication.

Firmer evidence that many young children with autism show gut symptoms may also improve care, alerting health care professionals to the comorbidities potentially accompanying ASD.

Gut links in autism

A correlation between having autism and showing gut symptoms does not prove a causal link between the two. The last story immediately above makes it tempting to think otherwise.

If gastrointestinal (GI) problems and autism do prove to be related, is this a causal link, and if so, what is the main direction of the cause? Is it a case of GI problems leading to autism, or autism leading to GI problems?

One very popular story in 2015 was that of a father being inspired after his child's autism improved following a course of antibiotics.

Again, cause is far from proven by a correlation in one child, especially when observed by a father, John Rodakis, who is passionate about researching such a link.

But Rodakis outlines that ASD "frustrates parents" when it comes to definitions, causes and care, and he believes a number of such "clinical trials of one" could contribute to the exploration of whether gut bacteria do play a role in ASD.

Skip to the year's top stories about gut bacteria concerning other conditions.

Blindness

Cancer

Every year brings a raft of new developments in cancer, and these past 12 months have been no exception, including:

It is well known in pathology that cancers arise out of a mix of genetic accidents and environmental triggers (or, rarely, genetic faults are inherited). Medical news is usually dominated by the external influences on cancer risk, often asking what is the latest risk factor that could be worth reducing?

One of the major cancer stories of 2015, however, was that it may be possible that up to two thirds of neoplasms are attributable to random DNA mutations during cell division, with no obvious environmental cause. The study suggested, in other words, that 22 of 31 cancer types were largely down to bad luck.

The findings were so striking that they prompted other researchers to take a different approach to the analysis, which reached a contradictory headline conclusion, that most cancer cases were "not caused by bad luck."

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Earlier this year, the World Health Organization stated that the consumption of processed meats could cause colorectal cancer.

Nonetheless, even in avoidable cases of cancer, avoidance is not always that easy - and some cases of cancer are still down to pure bad luck.

Further, scientists often need to have observed lots of cancer cases before being able to spot the links with any risk factors. Many of the external cancer factors may be as yet unknown.

It is a complex disease, which is not made clearer by the fact that even known carcinogens do not always lead to a cancer, and some cancers firmly linked to a carcinogen are not always caused by it.

An example of this is that some smokers do not get lung cancer, and some lung cancers are in people who have never smoked.

But it is common sense to leave the statistics aside and simply avoid making a choice that is known to increase risk.

The newly asserted links that came in 2015 included the one from the World Health Organization (WHO) declaring that eating processed meats raised the risk of colorectal cancer, and from the study linking increased sitting time with breast and ovarian cancer risks.

Not content with its already proven health effects elsewhere (see pregnancy and childbirth, for example) - could aspirin prove useful against cancer, too? These headlines were enticing prospects:

If you worship your daily coffee, you would be delighted with its regular appearance in the medical news, more often than not for positive reasons, as covered in the next section. Meanwhile, its benefits were also cited in cancer news articles this year:

Coffee

Drinking coffee may fall into the lifestyle category below, but it gets its own separate mention here because every year it never fails to be the subject of numerous research studies. It made some of the headlines in the cancer section immediately above, and here are more key developments involving coffee from 2015:

For more medical developments concerning what we consume, skip to the section about lifestyle.

Concussion and traumatic brain injury

Receiving extra attention from the medical research community in 2015 was the question of head injury caused by popular sports such as football and fighting, as witnessed by these headlines:

Cystic fibrosis

Cystic fibrosis has long been a challenging and life-limiting respiratory condition, but 2015 brought new hope:


Continue to the next page for more of the topics making a strong showing in the medical news of 2015, including Alzheimer's disease, Ebola, fertility, HIV infection and lifestyle.

Dementia and Alzheimer's disease

Dementia involves impairment to memory, communication and thinking (cognitive impairment). Alzheimer's disease is the best known and most common form of dementia, and it causes cognitive decline.

A report in August found the occurrence of dementia may be stabilizing in western Europe, but diseases of cognitive decline continue to receive more attention from governments and politicians.

Looking back to MNT's review in 2013, for example, dementia was rising then to the top of the political agenda for health, with the US enacting the first national plan for Alzheimer's disease and the UK hosting a G8 summit on dementia.

Prevention of Alzheimer's disease

A cure for Alzheimer's disease is yet to be found, and there is no firm evidence that it can be prevented. But there are many clues, and while the strongest risk factors known to date - such as genetics and age - cannot be avoided, there may be lifestyle measures that can reduce our risk and help us to enjoy healthier aging.

Among the risk factors for Alzheimer's disease, some are key for avoiding other serious illnesses such as stroke, which itself can lead to a form of dementia.

Current dementia tests

When is a dementia diagnosis made? After a lot of cognitive testing is the answer - but scoring six or under against a 10-question quiz is one early part of typical testing. Examples:

  • What is your age?
  • What year are we in?
  • Count backward from 20 to 1.

Learn more about diagnosing dementia

How great would it be if steps toward healthy aging could include a little of the things we enjoy? It may be that it could: a compound in red wine was found to stabilize an Alzheimer's biomarker.

But would we get enough of this compound from drinking wine? If not, there was also news that scientists grew industrial quantities of the compound using tomatoes.

Yet another treat that many of us enjoy could prove useful against dementia, too; one study asked if cocoa could hold a key to Alzheimer's prevention.

Here, neurology scientists, whose research had suggested that the polyphenols in cocoa could have brainpower benefits, wrote a paper outlining some of the opportunities of chocolate - but also some of the difficulties of "bottling" this potential.

How can any preventive benefits be derived from the right breeds of cocoa plant, how do you produce an extract and how would a dietary supplement work?

A US nonprofit has told New Scientist: "You can't possibly consume enough resveratrol from food sources to reach the doses that were used" in the research.

In other dementia news, a study shed new light on how stress may raise risk of Alzheimer's. Skip to the section on stress for findings that relate to other conditions.

Other notable Alzheimer's headlines from the past year:

Ebola

Back in 2014, the spread of Ebola became not just the biggest medical news story, but also one of the biggest stories of all the news across the media that year (as reflected in our 2014 review).

In 2015, thankfully, the threat subsided. Our news reported on successes against the spread of the epidemic, some of the lessons learned from it and research hopes for tackling future outbreaks:

Another tropical disease, malaria, saw a scientific breakthrough this year that could lead to treatments for severe cases of the disease that have not been reached at an early stage.

The "groundbreaking" discovery was made when researchers worked out what was causing many of the cases of death when the infection affects the brain.

Female sexual dysfunction

A number of well-established disorders are comprised by male sexual dysfunction, including erectile dysfunction - which in some cases is suitable for drug treatment - and ejaculatory disorders. But the idea of pharmaceutical treatment for a female sexual dysfunction in the form of low sexual desire is controversial.

Nonetheless, a drug that has become popularly misnamed "female Viagra" was approved by the US Food and Drug Administration (FDA) for use in women's acquired, generalized hypoactive sexual desire disorder (HSDD).

In spite of two previous, failed attempts to get the drug onto the market for women, flibanserin (which is not the same as the Viagra-branded drug, sildenafil) was finally approved in August.

To overcome the drug regulator's safety concerns, the approval allows prescriptions to be written only by specially authorized clinicians who are trained in managing the risks.

Fertility and IVF

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The UK government decided to allow genetic material from a third person to be used in IVF.

The big news in IVF (in vitro fertilization) this year was the UK's decision to allow genetic material from a third person to be used in the test tube creation of an embryo by two parents who would otherwise pass on a devastating genetic disorder.

The correction of faulty genes is now enabled in Britain's fertility clinics by mitochondrial donation, which was first approved by the country's parliament in early February.

We followed up that month with an article detailing the risks and benefits of the new procedure, along with information about the stance taken in the US.

In other fertility news for 2015, uterus transplantation was approved for 10 women in Britain.

Skip to the section on the next page covering the top news stories of the year about pregnancy and childbirth.

Flu

As the usual flu epidemic struck the US last winter, there was news across 2015 of progress toward better vaccination prospects:

Gut bacteria

The microbiome of the gut - the gastrointestinal system's population of microbial species - has been the feature of a number of medical developments this year:

Hair loss and baldness

The following research developments mostly concern male pattern baldness (though we have also produced an overview of what hair loss means for women):

HIV infection and AIDS

Lifestyle effects on health

One of the perennially big topics in medical news - lifestyle - concerns the numerous ways we choose to live our normal lives that impact on health.

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A number of infographics concerning the effects of junk food on the body went viral on social media this year.

Subjects here include diet, exercise and obesity. But surging for prominence in 2015 was the identity of added sugar as a culprit for bad health:

That last story about Coca-Cola centered on an infographic that spread around social media. This was soon followed by two more infographics forming the basis of these stories:

In other lifestyle news for 2015, a "love hormone" nasal spray could reduce calorie intake in men; vitamin C was "as effective as exercise" for obesity vascular health; and lack of exercise was found to be "twice as deadly" as obesity; while sedentary behavior featured in the following six stories.

Sedentary behavior


Continue to the next page for more of the topics making a strong showing in the medical news of 2015, including marijuana, mental health, stress, sleep and everyday psychology.

Marijuana

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Debate continues over the role and legal status of marijuana across the US.

American states began to legalize medical marijuana in earnest in 2014, kicking off more research into the drug's effects.

The trend has continued in 2015, including news that marijuana use has doubled since 2001.

Findings in favor of marijuana:

Findings against marijuana:

Mental health

Several studies have looked at the causes, development and prevention of different mental conditions.

Depression

Giving new coverage to the issue of mood disturbance in older people, the following articles looked at examples of depression being possibly preventable - and certainly not being inevitable - in older age:

Also in 2015 was the story about a taskforce that advises the US government on health prevention, which called for doctors to screen all adults for depression.

Causes of mental illness

A superficial reading of the headlines for the following three stories might lead you to worry about the effects of cats, creativity and psychedelic drugs.

But looking more closely at the details of each story reveals a few intriguing areas of inquiry from the wider scientific effort to understand the brain and how it becomes ill:

Moving from psychiatry, skip ahead to two findings concerning everyday psychology.

Paralysis

Pregnancy and childbirth

Sleep

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Researchers have continued to investigate how much sleep we should aim to get each night.

The question of roughly how much sleep we need each night concerns all of us, not just those with a sleep disorder or an interest in sleep medicine.

Could 6.5 hours be enough? That figure comes from a study that extrapolated the average sleeps of surviving hunter-gatherer societies, to propose what we might have needed before agriculture and industrialization.

Another way of answering the question may be to see what happens when we get too little or too much sleep. Here are three medical news stories in 2015 that linked poor sleep with risks of heart attack and stroke:

Stem cells

Two of the following stories concerning stem cell developments come with links to other topics covered on this page:

Stress

Headlines are not long enough to clarify what is meant by "stress" exactly - and not all stress is bad. Our bodies are well adapted to react healthily to life's stressors.

But being continually exposed to the things that trigger our flight-or-fight mechanisms, or having out-of-kilter responses to these stressors, can do us harm:

So what can we do about the risks of stress? According to one study this year, dishwashing could help. Or use MNT's spotlight page from February - it outlines some of the surprising implications for health - and some ways to tackle stress.

Also in the past year

Everyday psychology

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The infamous dress
Image credit: Tumblr

Men are "more narcissistic and entitled than women" - the male writer of this end-of-year review will avoid giving comment on this story and let you read it in full for yourself, except to say that the research behind it looked at three areas of personality:

  • Leadership/authority
  • Grandiose/exhibitionism
  • Entitlement.

Innovative medical technologies

And finally, 'the dress'

Scientists look at "The Dress" and answer the color conundrum - an optical illusion caused a stir across social media but was soon given a full academic treatment in the journal Current Biology.