Q. What is a placebo group and why do clinical trials have one?

A. A placebo is a dummy or inactive medication. Many trials use a placebo medication as a comparison for an active treatment medication. This is to test whether the active treatment is more effective in treating a particular disease, and to control for the ‘placebo effect’ where patients may feel they are getting better simply because they have been given a new medication.

Q. What is a randomised trial?

A. In a randomised trial the participants will be allocated to a treatment group by chance. The treatment group may have different doses of the same medication, different medications, or an active medication and a placebo. This is done randomly and usually by a computer to prevent bias within the research trial.

Q. What does ‘double-blinded’ mean?

A. This means that both the research team and the research participant will not know which treatment group the participant has been assigned to. This blinding can be broken (treatment revealed is revealed) only if there is a safety concern, as judged by the clinical team.

Q. How long does the study last for and what happens at the end of the clinical trial?

A. Studies usually last between six months to two years. At the end of the trial participants sometimes have the option to take part in an extension of that trial. During the extension all participants usually receive the active treatment and would continue until the medication is licensed for use in the UK. Not all trials have this option. If a trial does not have this option a patient may have to stop taking the trial medication/placebo at the end of the study period. This would not affect any other treatment or care they are receiving outside of the trial.

Q. What happens if something goes wrong?

A. It is rare for something to go wrong as clinical trials are carefully designed to make sure the patients’ safety is the top priority. The research team will complete physical health checks, such as a blood test, regularly during the study to monitor for any problems. Participants will also be given an emergency contact card in case they have any worries or concerns at any time including overnight or at weekends.

Q. Can I expect medication side effects while on a trial?

A. All medications carry a risk of side effects. Early stage clinical trials (Phase One) investigate the possible side effects for a particular medication and how often these occur. Medication can only be tested further (Phases Two and Three) if it is generally well tolerated in Phase One.

Our unit most commonly undertakes Phase Two or Three trials. This means participants will have a good understanding of the risk of any common side effects before taking part.

Q. Do research participants get paid? Can I be reimbursed for travel expenses?

A. Participants are not usually paid to be involved in later stage research trials (Phase Two or Three), however, they typically get their travel expenses and refreshments reimbursed on the days they attend a research appointment.

Q. What is an MRI Scan and a PET scan?

A. MRI (Magnetic Resonance Imaging) scans use magnetic fields and radio waves to produce images. An MRI scan of the head produces a detailed image of the brain.
Positron emission tomography (PET) scan is an imaging test of the brain. It uses a tracer to look for disease or injury in the brain.

Q. Will I get I get my test results back?

A. When participants take part in a study, their physical health is closely monitored and any test results are reviewed by the study doctor. Participants will always be informed if any test results are of concern or require further action, for example, if a repeat blood test is needed. Although trial data will not be relayed to the participants as it could affect the results.

Q. Can I take other medication at the same time?

A. Usually it is fine to continue to take current medications as long as they are at a stable dose with no side effects and are being taken as prescribed. Sometimes prescribed treatments cannot be taken with certain trial medications, and these would be specific to each trial. The current medications that are prescribed for Alzheimer’s disease and dementia are allowed to be taken.

Q. What happens if I change my mind?

A. Patients are able to change their mind at any time during the course of a clinical trial. They do not have to give a reason and it will not affect their clinical care outside of the trial.

The participants and their study partner’s best interests are a top priority for the unit at all times.

Q. How often will I have to visit?

A. Each clinical trial will have a slightly different appointment schedule. However, generally patients visit the hospital once a month or once every few months for a trial appointment. At the beginning of a study (the ‘screening’ process), appointments will be a little more frequent. Participants will know well in advance when appointments are due to help with holiday and other planning.

Q. Will joining a trial affect my other medical appointments?

A. No, it is important to note that you should continue attending other appointments as the trial does not replace your clinical care. Your doctors should be informed of your participation in the trial.


Some patients find it helpful to talk with their GP and memory clinic doctor or nurse. Alternatively the Imperial College Healthcare patient advice and liaison service (PALS) is a great source of independent advice about NHS care. You can contact PALS by calling 020 331 27777or sending an email to imperial.PALS@nhs.net