Huntington’s disease is a genetic disorder which generally affects people in their 40s or 50s, and primarily affects the brain – it results in a gradual loss of control of movement, memory and general mental ability. This condition is also linked to personality changes and depression, as well as some other mental illnesses. While there is no current treatment for HD, researchers have discovered many avenues for hope which could improve the quality of life for sufferers and their carers. This is an inherited condition which usually occurs in people who have a family history of the disease, and it is caused by a faulty gene on chromosome 4. In rare cases, there may not be a family history of the condition – in these cases, there may be a lack of diagnoses in the family or the condition being misdiagnosed as a mental illness with fidgetiness. Around 8 in every 100,000 people in the UK have HD, which accounts for around 4,800 people. The chromosomes are where the body stores our genetic information, in the form of DNA, so HD affects both genders equally – this means that you can inherit it from your mother or father in equal measure. The symptoms begin to show in middle age, but some reports have shown that there is a link to developing the condition in early age and inheriting it from the father, as opposed to the mother.
There are a number of brain activities affected by HD and the symptoms become more apparent between 30 and 50 years of age. The early signs of the condition include uncontrollable muscular movements, memory problems, a change in mood and stumbling. The mood alterations are one of the earliest signs of the disease, which are then followed by issues with memory and abnormal movements. Death usually occurs 15 to 20 years after the first symptoms appear, usually as a result of other sedentary illnesses such as pneumonia or specific causes such as difficulty swallowing which leads to choking.
Having Huntington’s disease is a difficult disease to cope with, and one of the more common side effects in sufferers is depression. It’s difficult for researchers to know if this is caused by circumstance or if it is because of the brain that HD causes. Researchers believe that mice who have been genetically engineered to have a mutated human HD gene may become depressed, which could offer a huge insight into the condition and how it affects our mood. Unfortunately, researchers need to adapt an animals DNA in order to research how they deal with HD, as they get it naturally in contrast to humans. Having carried out basic behaviour tests in mice, they can tell which of the mice are ‘depressed’ by how apathetic they are, in the same way that humans become apathetic when they’re depressed. In the mice, when the mutant Huntington’s disease gene was turned off in the hypothalamus, the mice showed less depression during the behavioural test. This study is still in the early stages but shows that certain areas of the brain may contribute to depression in HD – follow-up studies may show how a dysfunctional hypothalamus could lead to depression. The research does mean that whole-brain approaches to treatment may be very effective in terms of HD. Those which target just the hypothalamus could be lacking in strength and may not be enough to control depression caused by the disease. This could be beneficial for researchers working on treatments such as gene silencing which could mean treatments are injected into specific brain areas.
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