An article published this week in the prestigious journal Nature Medicine documents what is believed to be the first evidence that Alzheimer’s disease can be transmitted from person to person.

The finding arose from long-term follow up of patients who received human growth hormone (hGH) that was taken from brain tissue of deceased donors.

Preparations of donated hGH were used in medicine to treat a variety of conditions from 1959 onwards – including in Australia from the mid 60s.

The practice stopped in 1985 when it was discovered around 200 patients worldwide who had received these donations went on to develop Creuztfeldt-Jakob disease (CJD), which causes a rapidly progressive dementia. This is an otherwise extremely rare condition, affecting roughly one person in a million.

What’s CJD got to do with Alzehimer’s?

CJD is caused by prions: infective particles that are neither bacterial or viral, but consist of abnormally folded proteins that can be transmitted from cell to cell.

Other prion diseases include kuru, a dementia seen in New Guinea tribespeople caused by eating human tissue, scrapie (a disease of sheep) and variant CJD or bovine spongiform encephalopathy, otherwise known as mad cow disease. This raised public health concerns over the eating of beef products in the United Kingdom in the 1980s.

Human growth hormone used to come from donated organs

Human growth hormone (hGH) is produced in the brain by the pituitary gland. Treatments were originally prepared from purified human pituitary tissue.

But because the amount of hGH contained in a single gland is extremely small, any single dose given to any one patient could contain material from around 16,000 donated glands.

An average course of hGH treatment lasts around four years, so the chances of receiving contaminated material – even for a very rare condition such as CJD – became quite high for such people.

hGH is now manufactured synthetically in a laboratory, rather than from human tissue. So this particular mode of CJD transmission is no longer a risk.

What are the latest findings about Alzheimer’s disease?

The Nature Medicine paper provides the first evidence that transmission of Alzheimer’s disease can occur via human-to-human transmission.

The authors examined the outcomes of people who received donated hGH until 1985. They found five such recipients had developed early-onset Alzheimer’s disease.

They considered other explanations for the findings but concluded donated hGH was the likely cause.

Given Alzheimer’s disease is a much more common illness than CJD, the authors presume those who received donated hGH before 1985 may be at higher risk of developing Alzheimer’s disease.

Alzheimer’s disease is caused by presence of two abnormally folded proteins: amyloid and tau. There is increasing evidence these proteins spread in the brain in a similar way to prion diseases. So the mode of transmission the authors propose is certainly plausible.

However, given the amyloid protein deposits in the brain at least 20 years before clinical Alzheimer’s disease develops, there is likely to be a considerable time lag before cases that might arise from the receipt of donated hGH become evident.

When was this process used in Australia?

In Australia, donated pituitary material was used from 1967 to 1985 to treat people with short stature and infertility.

More than 2,000 people received such treatment. Four developed CJD, the last case identified in 1991. All four cases were likely linked to a single contaminated batch.

The risks of any other cases of CJD developing now in pituitary material recipients, so long after the occurrence of the last identified case in Australia, are considered to be incredibly small.

Early-onset Alzheimer’s disease (defined as occurring before the age of 65) is uncommon, accounting for around 5% of all cases. Below the age of 50 it’s rare and likely to have a genetic contribution.

The risk is very low – and you can’t ‘catch’ it like a virus

The Nature Medicine paper identified five cases which were diagnosed in people aged 38 to 55. This is more than could be expected by chance, but still very low in comparison to the total number of patients treated worldwide.

Although the long “incubation period” of Alzheimer’s disease may mean more similar cases may be identified in the future, the absolute risk remains very low. The main scientific interest of the article lies in the fact it’s first to demonstrate that Alzheimer’s disease can be transmitted from person to person in a similar way to prion diseases, rather than in any public health risk.

The authors were keen to emphasise, as I will, that Alzheimer’s cannot be contracted via contact with or providing care to people with Alzheimer’s disease.

Steve Macfarlane, Head of Clinical Services, Dementia Support Australia, & Associate Professor of Psychiatry, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What do you imagine a good night’s sleep to be?

Often when people come into our sleep clinic seeking treatment, they share ideas about healthy sleep.

Many think when their head hits the pillow, they should fall into a deep and restorative sleep, and emerge after about eight hours feeling refreshed. They’re in good company – many Australians hold the same belief.

In reality, healthy sleep is cyclic across the night, as you move in and out of the different stages of sleep, often waking up several times. Some people remember one or more of these awakenings, others do not. Let’s consider what a healthy night’s sleep looks like.

Sleep cycles are a roller-coaster

As an adult, our sleep moves through different cycles and brief awakenings during the night. Sleep cycles last roughly 90 minutes each.

We typically start the night with lighter sleep, before moving into deeper sleep stages, and rising again into rapid eye movement (REM) sleep – the stage of sleep often linked to vivid dreaming.

If sleeping well, we get most of our deep sleep in the first half of the night, with REM sleep more common in the second half of the night.

Adults usually move through five or six sleep cycles in a night, and it is entirely normal to wake up briefly at the end of each one. That means we might be waking up five times during the night. This can increase with older age and still be healthy. If you’re not remembering these awakenings that’s OK – they can be quite brief.

What does getting a ‘good’ sleep actually mean?

You’ll often hear that adults need between seven and nine hours of sleep per night. But good sleep is about more than the number of hours – it’s also about the quality.

For most people, sleeping well means being able to fall asleep soon after getting into bed (within around 30 minutes), sleeping without waking up for long periods, and waking feeling rested and ready for the day.

You shouldn’t be feeling excessively sleepy during the day, especially if you’re regularly getting at least seven hours of refreshing sleep a night (this is a rough rule of thumb).

But are you noticing you’re feeling physically tired, needing to nap regularly and still not feeling refreshed? It may be worthwhile touching base with your general practitioner, as there a range of possible reasons.

Common issues

Sleep disorders are common. Up to 25% of adults have insomnia, a sleep disorder where it may be hard to fall or stay asleep, or you may wake earlier in the morning than you’d like.

Rates of common sleep disorders such as insomnia and sleep apnoea – where your breathing can partially or completely stop many times during the night – also increase with age, affecting 20% of early adults and 40% of people in middle age. There are effective treatments, so asking for help is important.

Beyond sleep disorders, our sleep can also be disrupted by chronic health conditions – such as pain – and by certain medications.

There can also be other reasons we’re not sleeping well. Some of us are woken by children, pets or traffic noise during the night. These “forced awakenings” mean we may find it harder to get up in the morning, take longer to leave bed and feel less satisfied with our sleep. For some people, night awakenings may have no clear cause.

A good way to tell if these awakenings are a problem for you is by thinking about how they affect you. When they cause feelings of frustration or worry, or are impacting how we feel and function during the day, it might be a sign to seek some help.

We also may struggle to get up in the morning. This could be for a range of reasons, including not sleeping long enough, going to bed or waking up at irregular times – or even your own internal clock, which can influence the time your body prefers to sleep.

If you’re regularly struggling to get up for work or family needs, it can be an indication you may need to seek help. Some of these factors can be explored with a sleep psychologist if they are causing concern.

Can my smart watch help?

It is important to remember sleep-tracking devices can vary in accuracy for looking at the different sleep stages. While they can give a rough estimate, they are not a perfect measure.

In-laboratory polysomnography, or PSG, is the best standard measure to examine your sleep stages. A PSG examines breathing, oxygen saturation, brain waves and heart rate during sleep.

Rather than closely examining nightly data (including sleep stages) from a sleep tracker, it may be more helpful to look at the patterns of your sleep (bed and wake times) over time.

Understanding your sleep patterns may help identify and adjust behaviours that negatively impact your sleep, such as your bedtime routine and sleeping environment.

And if you find viewing your sleep data is making you feel worried about your sleep, this may not be useful for you. Most importantly, if you are concerned it is important to discuss it with your GP who can refer you to the appropriate specialist sleep health provider.

Amy Reynolds, Associate Professor in Clinical Sleep Health, Flinders University; Claire Dunbar, Research Associate, Sleep Health, Flinders University; Gorica Micic, Postdoctoral Research Fellow, Clinical Psychologist, Flinders University; Hannah Scott, Research Fellow in Sleep Health, Flinders University, and Nicole Lovato, Associate Professor, Adelaide Institute for Sleep Health, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.