Different studies use different techniques to find out about HD. Here are some of the commonly used techniques we use.

A patient about to have an MRI brain scan

Magnetic Resonance Imaging (MRI) scans

MRI brain scans are detailed, 3-dimensional images of the brain. A powerful magnet is used to obtain the images, but no x-rays are used.

MRI scans are very safe unless there is any metal in or on your body, for instance metal skull implants or pacemakers. We always complete a safety check to make sure it will be safe.

MRI scanners are quite loud, so patients are required to wear ear-plugs or headphones for the scan.

You will be asked to lie flat on the scanner table and made comfortable. The scanner camera will be placed above your head and the table will slide into position. MRI scanners tend to be quite narrow tunnels. You can be seen and heard at all times, and the scanner technicians can speak to you as well. Most people can tolerate this well (some people even fall asleep), but if you’re claustrophobic it might be best not to volunteer for studies involving MRI scans.

Neuropsychology testing

We know that most people with HD develop subtle changes in the thinking process before they show the abnormal movements (chorea). Many of our studies use thinking tasks (known as neuropsychometry tasks) to get an accurate idea of what types of thinking, if any, are affected.

Some tests are written, others spoken, and some are computer-based although you do not need any prior knowledge of computers in order to do them.

Most studies use a range of tasks to look at different aspects of thinking, such as memory, recognising pictures or naming things. Everyone has different strengths and weaknesses, so most people find that they do well on some tasks but feel that they are not doing so well on others. This is perfectly normal. A lot of the tasks are designed to detect very small changes, so they sometimes get harder towards the end. Again, it is perfectly normal not to be able to answer all the parts of a particular task.

If anything worries you during or after a study visit, there are opportunities to be referred to a clinical psychologist at the hospital to have a formal assessment of some aspects of your thinking. You will not normally be told specific results of any neuropsychology tasks that you do as part of a research study.

Clinical testing

Nearly all studies involve clinical tests of one kind or another. At a simple level, this may be the brief neurological examination we use to identify signs of HD. Other studies are looking at new clinical tests, such as computerised measurement of eye movements, to find out more about HD.

Blood and urine tests

Some studies, like the Biomarkers Project, use blood and urine tests as the main source of information and research material.

In other studies, we may ask for a blood sample to find out more about you medically. For instance, in a treatment trial, we usually take blood to look for conditions like diabetes or raised cholesterol, that might have an effect on your health or the treatment.

We sometimes ask whether we can take a blood sample to repeat the genetic test for HD. This is because we can now accurately measure the length of the abnormal gene (CAG repeat length) and it can be a useful measurement when we compare it with other research findings from patients in a study.

Treatment trials

Studies that involve measurements, tests or scans are called observational because they do not involve treatments. They are important so we can find out more about HD and how best to measure and predict its progression.

But we are increasingly interested in testing possible treatments for HD. Where possible, we compare possible treatments with a placebo — a dummy treatment (for example, a pill that looks the same as an active drug but doesn’t contain any medication). This is so we can be sure any benefit we observe is due to the treatment rather than simply being involved in the trial.

Sometimes, treatment trials are blinded, meaning that we will not tell you whether you are receiving the treatment or the placebo, and which one you get may be decided at random. In some trials, the trial organisers do not know until the end which patients have been taking the active treatment or placebo. These studies are called double blind. This helps to improve the reliability of the results.

Updated January 11, 2010