Can Parkinson’s risk be reduced?

We all know that saturated fat is bad for us, smoking increases the risk of cancer, and alcohol can damage our livers. But some studies suggest there may be ingredients within these vices that have surprising properties.

What do nicotine, high cholesterol and caffeine have in common?

The answer is that studies have indicated they may reduce the risk of Parkinson’s.

Parkinson’s is caused by a complex combination of lifestyle, environmental and genetic factors. Around one in 20 people with Parkinson’s have inherited changes in their genetics that play an important role. But for the other 95% of people who are diagnosed, the cause is unknown. Most people will be diagnosed seemingly at random. This type of Parkinson’s is called sporadic.

sporadic

/spəˈradɪk/ Occurring at irregular intervals or only in a few places; scattered or isolated.

Because there are so many factors that can influence risk of Parkinson’s, for the vast majority of people, putting a finger on the one thing that may have caused the condition is impossible.

It is the way many different risk factors work together that means it is very hard to predict who will develop Parkinson’s or pinpoint the cause. And, in situations where multiple people may have been exposed the same risk factors, not all will develop Parkinson’s. But while lifestyle, genetics and environment may all play a role, not all these factors necessarily increase risk.

Researchers know that risk can go up or down, and certain factors are known to decrease Parkinson’s risk. And some of the most interesting pieces of research suggest things that are known to be bad for us may decrease risk of Parkinson’s.

1. Nicotine

Smoking is one of the biggest causes of death and illness in the UK. We now know smoking increases the risk of over 50 serious health conditions, from cancer and heart disease to stroke and dementia. Public knowledge of these risks are why many smokers are attempting to quit, and has led to the prevalence of smoking decreasing gradually over the last 40 years.

But a number of studies have suggested that smokers could have up to a 70% reduce risk of developing Parkinson’s. These large scale studies show the longer someone has smoked the lower their risk, and that stopping smoking reduces the protective effect against Parkinson’s.

Other studies involving identical twins highlight there are fewer cases of Parkinson’s in smokers compared to their non-smoking twins.

So what is going on? Researchers believe it could be the nicotine in cigarettes that is protecting the dopamine producing cells in the substantia nigra. In some animal models of Parkinson’s nicotine appears to protect these precious cells from toxic chemicals. But more research is needed to fully understand how exactly nicotine may be protecting the brain.

Nicotine may have other interesting properties when it comes to managing the symptoms of Parkinson’s. Professor Steph Cragg is a researcher at the Oxford Parkinson’s Disease Centre. She is interested in how nicotine could led us to a new treatment for Parkinson’s:

What inspired you to study this area of Parkinson’s research?
“I was inspired by the idea that we could use nicotine to develop better treatments for Parkinson’s.
“In typical brains, nicotine can stimulate nerve cells to boost dopamine levels. Importantly, the ‘receptors’ that detect and respond to nicotine may allow nerve cells to release dopamine only when it’s needed, which could reduce side effects.
What have you found?
“We found that nicotine receptors control dopamine release in Parkinson’s brains, but in a different way to non-Parkinson’s brains.
“We also discovered that the alpha5 type of nicotine receptor is the main controller of dopamine in the areas of the brain that are affected in Parkinson’s — but not in other areas of the brain.
How will your research help people with Parkinson’s?
“Our research shows it may be possible to design new drug treatments which specifically target the alpha5 nicotine receptor.
“We hope that these drugs would only work in the areas of the brain affected in Parkinson’s, and could be the key to better therapies with fewer side effects for people living with the condition.” — Professor Steph Cragg

The take home message…

There is quite a lot of evidence pointing towards smoking decreasing the risk of Parkinson’s. But this does not outweigh the fact that smoking increases the risk of other conditions, such as lung and mouth cancer, by a far greater extent.

There are alternatives to smoking, but at the moment there is a lack of evidence that nicotine replacement therapies, such as patches or gum, have the same effects on reducing Parkinson’s risk. And studies of nicotine patches to treat the symptoms of Parkinson’s have, so far, produced conflicting and therefore inconclusive results.

But there are other alternatives if you want more nicotine in your life. Nicotine-containing vegetables come from the same botanical family as tobacco, Solanaceae, and include tomatoes, potatoes, and peppers. And, even though these vegetables only contain small amounts of nicotine, in one small study they were associated with a reduced the risk of Parkinson’s compared to other types of vegetables.

While eating a few more fruits and vegetables will probably be good for most people, we recommend talking to a healthcare professional or specialist before making significant changes to your diet or taking supplements.

2. Alcohol

The association between alcohol and Parkinson’s risk is not as clear cut as smoking. There have been a number of studies, but the results are inconclusive.

The studies that show the greatest association may be unintentionally biased. And those that are less likely to be biased show little to no change in risk. At best, any decrease in Parkinson’s risk obtained through consuming alcohol is too small to produce any measurable effect.

However, there is some evidence that the type of alcohol matters.

Researchers have suggested that antioxidants in red wine could protect brain cells, and that a chemical in hops, a key component in beer, may be of use in developing new treatments that slow the progression of Parkinson’s.

Xanthohumol, the molecule in hops, has been investigated using brain cells grown in the lab similar to those lost in Parkinson’s. The researchers showed that xanthohumol protected these cells from oxidative stress — a process that is believed to play a key role in Parkinson’s.

Oxidative stress happens when there are too many damaging molecules called free radicals inside our bodies. Our bodies constantly produce free radicals and unchecked, these molecules can cause damage to our cells and tissues. Oxidative stress is believed to contribute to the death of brain cells in Parkinson’s.

Antioxidants are known to help to protect cells from oxidative stress. Red wine contains potentially beneficial polyphenols known as flavonoids, which may act as antioxidants. And in one study, high intake of flavonoids (from tea, berry fruits, apples, red wine, and oranges or orange juice) was seen to reduce the risk of Parkinson's by up to 40% but only in men.

There have also been studies to test antioxidants as a treatment for Parkinson’s, but so far the results have been disappointing. But researchers still believe tackling oxidative stress in Parkinson’s may be key to developing treatments that slow or stop its progression.

The take home message…

Increasing your alcohol intake is not recommended for your health. Treatments that tackle oxidative stress may hold promise for Parkinson’s, but the prescription is not going to be a glass of wine a day.

There are healthier ways to get antioxidants — most fruits and vegetables are rich sources of antioxidants, which include vitamins A, B (riboflavin), C, and E.

While eating a few more fruits and vegetables will probably be good for most people, we recommend talking to a healthcare professional or specialist before making significant changes to your diet or taking supplements.

3. Fatty diet

High cholesterol can increase a person’s risk of cardiovascular disease, such as heart attack or stroke. But could high cholesterol protect brain cells from Parkinson’s? At least one study suggests so.

High cholesterol is caused by eating too much saturated fat, trans fat, and cholesterol. Saturated fat and cholesterol are in foods that come from animals, such as meats, whole milk, butter, and cheese. Trans fat is found in fried foods and packaged foods, such as cookies and crisps.

Obesity and lack of exercise can also contribute. And the UK has been described as suffering from an obesity epidemic — obesity levels have trebled in the last 30 years and more than half the population could be obese by 2050. At the moment, the UK are topping Europe’s obesity league.

So as the heaviest country, it makes sense that the UK is the statin capital of Europe as doctors try to combat high cholesterol levels and the increased risk of heart disease.

Statins are medicines that can help lower rates of low-density lipoprotein (LDL) cholesterol (so-called “bad” cholesterol) in the blood. High rates of LDL cholesterol can lead to hardening and narrowing of the arteries. So reducing LDL levels by using statins can reduce cardiovascular disease.

When it comes to cholesterol, statins, and Parkinson's risk, where do we stand?

A number of early studies suggested that statin use decreases Parkinson’s risk, however a study published in 2015 suggested the reverse might be true.

The research published in Movement Disorders suggests that high cholesterol might protect brain cells, so taking statins to reduce cholesterol may inadvertently be increasing Parkinson’s risk.

More recent research has concentrated on the use of statins for people who have already been diagnosed. The Tracking Parkinson's study has found that people recently diagnosed with Parkinson’s who are at high or medium risk of cardiovascular disease tend to have more problems with walking and memory.

Professor Donald Grosset, leader of the Tracking Parkinson’s study and one of the authors of a study into cardiovascular health in Parkinson’s, explains:

“It’s not surprising that many people living with Parkinson’s also have an increased risk of cardiovascular disease as both conditions get more common as we get older.
“But our study highlights the impact of living with both at the same time.
“People with poorer cardiovascular health had worse walking and memory even in the early stages of Parkinson’s, so improving cardiovascular health may help these aspects of the condition.
“We were slightly surprised that so few people in the high and medium risk groups were taking statins, since they are proven to reduce the risk of heart attacks and strokes.
“We hope our findings will help to start a conversation about vascular health in Parkinson’s, so that it can be assessed and, where appropriate, treated.” — Professor Donald Grosset

The take home message …

The research is inconclusive — the relationship between Parkinson’s risk and cholesterol may be more complex that it originally appeared to be. But for people who have already diagnosed with Parkinson’s, statins may help to improve some aspects of the condition.

We recommend talking to a healthcare professional or specialist before making significant changes to your diet or to discuss your medications.

4. Caffeine

On a list of things that are generally bad for us, caffeine is probably the odd one out. It is one of the most widely consumed substances, and for most people an occasional cup of coffee won’t do too much harm (although pregnant women and those with a sensitivity may have to be careful of their intake).

Caffeine is found naturally in lots of foods, such as coffee, tea and chocolate. And is added to some soft drinks, energy drinks, and cold and flu remedies.

Some studies have suggested that higher caffeine consumption may reduce the risk of developing Parkinson’s and have beneficial effects on some symptoms.

In one of the most recent studies, researchers found that higher caffeine consumption, from drinks like tea and coffee, was linked to the development of fewer motor and non-motor symptoms, and lower symptom severity. They also reported that people who drank more caffeine started Parkinson’s medication, such as levodopa, later compared to those with lower caffeine consumption — suggesting caffeine may be linked to slower development of Parkinson’s symptoms after diagnosis.

However, much of this research comes from small studies and some studies have been inconclusive. More evidence from larger clinical trials is still needed to further understand the relationship between caffeine and Parkinson’s risk before recommending people increase their caffeine intake.

But from the evidence so far, there might be a glimmer of hope that a brew might be good for you. Why?

Animal and cell models suggest that caffeine can protect the brain cells lost in Parkinson’s. Research suggests its neuroprotective effects, which allow caffeine to slow the progression of Parkinson’s in rodent models, comes through its interaction with the adenosine A2A receptors that help regulate glutamate signalling — another type of neurotransmitter in the brain.

Professor David Dexter, Deputy Director of Research at Parkinson’s UK, explains why glutamate may be important in Parkinson’s:

“In Parkinson’s, the lack of dopamine in Parkinson’s causes another chemical messenger called glutamate to become overactive, triggering the death of nerve cells and so some of the symptoms of Parkinson’s as it is toxic in large amounts.
“In our research project, we aimed to find out whether drugs that block glutamate activity, called mGluRs, can reduce Parkinson’s symptoms and protect nerve cells. Our second aim was to understand how these drugs work.
“Unfortunately we found that the protection was very small, and the drugs were not able to improve the motor symptoms seen in the animal model of Parkinson’s. This suggests these mGluRs aren’t promising drug targets for slowing down or stopping the progression of the condition.” — Professor David Dexter

Whilst these mGluRs might be a dead end, researchers are still investigating other compounds that target adenosine A2A receptors. And there have been reports of drugs with potential in the early stages of the research pipeline.

The take home message …

Although many of us consume caffeine on a daily basis, it is a drug and it can have side effects, especially if you’re someone who isn’t used to it. We would recommend talking to your GP or nurse before making any significant changes to your caffeine intake.


The information contained in this blog is not meant as health advice, and should not be used to diagnose or treat any medical condition. You should always consult a qualified health professional or specialist before making any changes to your diet, medications or supplement intake.