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How long is too long?

How long is too long?

We celebrate our birthdays to mark the fact that we have lived yet another year on planet Earth, but how many birthdays are too many? One of the greatest challenges facing contemporary medicine is not extending the lifespan of a person, but rather keeping that person in good health until their final days. Currently, our physical and mental health is threatened chiefly by neurodegenerative diseases with unknown aetiology. These neurodegenerative diseases were the subject of the lecture delivered by Dr hab. Grzegorz Kreiner from the Department of Brain Biochemistry of the Polish Academy of Sciences during the International Brain Awareness Week.

Almost all of us associate birthdays with cakes, parties and songs, but we rarely wonder about reaching old age. While our minds are still young and bodies are working well, we don’t want to contemplate the consequences of the passing of time. As year pass, we slowly start to realise that we’ll have to pay for things we trivialised in our everyday life: sleepless nights, busy days, toxic relationships, fast foods, drugs and alcohol, stress – the list goes on and on. What are the risks related to longer life and overexerting our bodies?

How to live a long and happy life?

Advances in medicine and good access to health care have given the countries of the Rich North a gift that was undreamt of by our ancestors: a longer life. The age of one hundred years is no longer treated as a mystical and unreachable. Living that long is still exceptional, but nowhere near as rare as it was in the past. The issue lies in living that long while maintaining good physical and mental health.

The most common neurodegenerative disease that affects the elderly is undoubtedly Alzheimer’s disease. Contrary to even the most advanced stages of cancer, it has no viable treatment. Slowly but inexorably, it robs a person of their life: memories, experiences, loved ones – all of these are irreversibly erased. Aside from enhancing cognitive processes in the initial stages, medicine can do nothing to help the victims of this terrible disease.

The second illness troubling people that have reached an advanced age is Parkinson’s disease, which is currently incurable as well. In this case, the situation is reversed: a person with a sound mind struggles with a failing body that is unable to perform even the simplest tasks – even eating dinner, going to the toilet or putting on clothes may prove difficult, and there is nothing to be done about it.

Curse of longevity

Once neurodegeneration starts, there is no way to stop it. Although we have extensive knowledge about the process, down to stages of neuron loss and observable symptoms, we are simply unable to utilise that knowledge in any meaningful way. The WHO estimates that if our population continues to age at the current pace, by 2050 about 100 million people in the world will be diagnosed with Alzheimer’s disease, while 12 million will suffer from Parkinson’s disease. This is troubling, to say the least.

Persistence of Memory by William Utermohlen. The artist was diagnosed with Alzheimer’s disease in 1995. His self-portraits are a harrowing depiction of the progressing illness. Source: http://digitalcommons.iwu.edu/utermohlen

In 90% of cases, Alzheimer’s disease remains idiopathic, which means that its cause is unknown. Scientists think that one of signs, or possibly ‘catalysts’ of its approach, is an excessive amount of Aβ and NFT proteins inside of neurons, but they’re still not sure how exactly they are related to the disease. More general causes of Alzheimer’s include chronic inflammations, vascular problems, stress, high levels of cholesterol and disorders of glucose metabolism. Additionally, about 10% of cases are caused by three genetic mutations (hereditary Alzheimer’s disease). This has been proven by animal testing on mice, giving rise to the idea of a vaccine that could eliminate the unwanted proteins from neurons and stop the illness. Unfortunately, no clinical trials so far have achieved success, despite promising results during animal trials. Alternative approaches have been tried in numerous research projects, e.g. those related to expression of gene coding proteins or the potential harmfulness of calcium ions. The latest developments related to the causes of Alzheimer’s disease are related to the bacteria causing periodontitis (Porphyromonas gingivalis). Although research has yet to show if good oral hygiene can save us from the illness, it’s definitely not a bad idea to take good care of it.

Parkinson’s disease is related to progressive loss of neurons responsible for producing dopamine. The lack of this neurotransmitter is a direct cause of loss of mobility, muscle stiffness and resting tremors ­– the most commons symptoms of the disease. The available methods of symptomatic treatment are only useful in concealing the progress of the illness. They are based on administering a drug that is a precursor of dopamine (it’s impossible to administer dopamine directly, as it can’t cross the blood-brain barrier). This type of therapy is only effective if the brain has enough active neurons that produce dopamine, so that they can be ‘boosted’. Unfortunately, these neurons eventually die, rendering the treatment meaningless: in this case, the brain may be compared to a construction site which receives regular transports of bricks, but lacks the workers to lay them. Even more unfortunate is the fact that the first symptoms of Parkinson’s only show themselves after more than 80% of neurons have already died off. As with Alzheimer’s disease, 90% of cases are idiopathic, while the remaining 10% are caused by genetic mutations related to 26 genes. The most promising treatment methods involve substances that could ‘revivify’ the neurons, but they are still a long way away. In recent years, some researchers have speculated that Parkinson’s disease is caused not only by the loss of dopamine, but noradrenalin as well. If these assumptions prove to be correct, new methods of symptomatic treatment could be devised. As the illness is usually diagnosed in people around sixty and develops over the course of several years, administering drugs that affect the noradrenergic system could delay it by 20–30 years, alleviating the problem.

Hope for the future

Modern methods of treatment of brain imaging allow for spotting neurodegenerative changes in their early stages. At the same time, the search for new markers of these diseases and employing innovative techniques in genetic engineering (such as the ‘molecular scissors’, awarded with this year’s Nobel Prize in Chemistry) give us more hope that in the future, we will be able to celebrate our one hundredth birthdays in good physical and mental condition.

Original text: www.nauka.uj.edu.pl

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