One way that we link genetics to a neurodegenerative disease is when we observe that a particular disease runs in families. For example, in 1872, George Huntington, a 22-year-old physician in the US, was the first to officially describe a type of chorea (uncontrolled, jerky movements) in a disease that came to bear his name – “Huntington’s disease”. Dr Huntington was part of a long line of physicians, and by carefully reviewing his father’s notes, he was able to see that the condition was hereditary. See more on Huntington’s disease here.
Nowadays, we can look at the DNA of patients to link genetics to a disease. For example, in 2003, researchers examined DNA samples from a large family with many members who had autosomal dominant Parkinson’s disease. When a disease is autosomal dominant, it affects everyone who carries the mutation, and the disease does not skip generations. The researchers found that a single mutation caused increased expression of a protein called alpha synuclein and this increased expression of alpha synuclein caused their disease. Learn more about Parkinson’s disease here.
With regard to how genetics and environmental factors interact, individuals carrying a particular mutation that causes Parkinson’s disease who live in the United States show a different disease duration when compared to their relatives who live in Italy – researchers believe environmental factors are the cause. In another example, following the Gulf war, many soldiers became ill with Gulf war syndrome, which causes problems with thinking, in addition to a host of other symptoms. The condition was due to exposure to a toxin, but only people with a mutation in a gene called PON1 developed the condition. The mutation in the gene lead to the expression of a defective Pon1 protein, that was less capable of breaking the toxin down. Thus, genetics and environmental factors do interact, and in fact, we believe that many diseases, including Parkinson’s disease and Alzheimer’s disease are caused by a combination of gene mutations and environmental factors.
When we use mice to “model” a particular disease, we must ensure that the cause of the disease in mouse and human is similar, and the symptoms displayed by the mouse is similar to the symptoms shown by patients. For example, excessive stress places humans at increased risk of depression, and stressed mice and rats also show symptoms of depression. A naturally occurring mutation in some mice leads to seizures and this mutation also leads to seizures in humans. In other lines of mice, we insert a mutant form of a gene that causes Alzheimer’s disease in humans into the mouse genome. All of these “models” are critical for greater understanding of depression, epilepsy and Alzheimer’s disease.
Mice are used all over the world to help understand human diseases. For example, in Parkinson’s disease, we know that the disease begins decades before diagnosis and this stage is very difficult to examine in humans because the individual is not ill. We can use mice and other animal “models” to understand disease mechanisms during these very early stages. We can also learn things like the best dose range to use for a particular therapeutic, or whether a sufficient amount of a therapeutic can get into brain. Therefore, through careful, ethical research using mice, we can learn a lot about human diseases and how to treat them.
Learn why we need to do careful research in animals here.
Learn how our standards of care for our mice and the research we do with them is governed by the law in Europe.
Physical and emotional pain are indeed related – for example, depression is a serious disorder that causes intense emotional suffering in the patient. An individual who is depressed is more likely develop chronic pain conditions, but also, someone with chronic pain is more likely to develop depression.
In a further link, drugs used to treat depression modulate levels of the brain chemicals noradrenaline and serotonin – and the same drugs can be used to treat chronic pain.
Moreover, the drug Ketamine is used to control severe pain and can be used as a general anaesthetic, but new data show that it is also useful for some patients with depression.
In rare cases, severe grief, anger or surprise can lead to physical pain like angina – this is called Broken Heart syndrome. It is most often seen in women, and it is caused by stress-related increased activity in an area of the brain called the amygdala. The amygdala controls emotions and some forms of learning and memory. Learn more about Broken Heart syndrome here.
Note that while under general anaesthesia, our brain is not capable of responding to pain or to any external signal. This is very important because the failure to respond normally to the pain of making an incision, for example, allows the surgeon to do their work.
All of this indicates that pain and depression share some brain pathways but we don’t yet fully understand why or how. Learn more about depression here.
Forgetting where you put the car keys or forgetting a monthly bill are examples of normal age-related memory loss. These problems don’t affect your ability to live your life and although annoying, they are part of our aging process.
More serious forms of memory loss can lead to problems like not remembering how to make a cup of tea, not remembering how to find your way home, not being able to figure out the correct date or having difficulty speaking with others. These may be signs of dementia, which is not normal aging. This kind of memory loss affects your ability to live your daily life.
We know that people who have higher childhood education levels and higher lifelong levels of education are less likely to develop Alzheimer’s disease, which is the most common form of dementia.
However, we must remember that our ability to go to college is affected by our socioeconomic status (our economic and social position relative to others).
A high socioeconomic status means that we can more easily go to college and it also means we eat better food, we are healthier and we have a better quality of life. So, education is not the only factor that protects us! As another example, people who work in jobs that require interaction with others are also less likely to develop Alzheimer’s disease.
As the saying goes – for your brain, we must use it or lose it!
Have a good diet and exercise regularly. Meet up with friends and have fun. Protect your head – wear a helmet when cycling and wear a seat belt in the car. All of these things, especially eating a proper diet and regular exercise, will help protect against memory loss.
Learn more about Alzheimer’s disease here.
Genetics account for about 50% of our intelligence.
One gene that has been studied is catechol-O-methyl-transferase (COMT). This gene encodes a protein that normally degrades dopamine in brain. This gene has some functional polymorphisms, which means that it has variants that differ by a single base position in its DNA. Individuals carrying some modified forms of the COMT gene show better working memory (short-term memory). However, there are likely many genes that affect intelligence, and each are likely to have a small effect.
In fact, super-intelligent people with intelligence quotients (IQs) of over 170 (the average IQ is 100), actually lack the many mutations that the rest of us have! Learn more about DNA here.
Also, remember that although 50% of our intelligence is controlled by our genes, 50% is controlled by something else – our childhood environment, our lifestyle, our diet, our healthcare, our education…
Also, although IQ is constant, we can improve our memory by regular training – this includes mental stimulation, for example education, and social interactions, as well as diet and exercise.
A great place to start is coming to Brain Awareness Week at the University of Tartu! We are so happy you came!
Indeed, a special goal of ours was to make a space for you, our visitor, to talk about neuroscience. Another goal is to create a special webpage within ut.ee that is dedicated to neuroscience.
Some great resources for further information are within the Federation of European Neurosciences website, here.
The Society for Neuroscience is an American organisation and they have developed a great resource for people interested in the brain here.
If you would like to get involved in neuroscience, simply review the laboratories within University of Tartu and send the laboratory head an email! It is really that simple! The University of Tartu has many programs to help you get involved in research, and Talendid Tartusse is a great program to help highschool students see and do research. Learn more here.