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2011: Ethics of dementia research


An allele is one member of two or more forms of a gene that is located in a specific position on a specific chromosome. Sometimes, different alleles can lead to distinct traits.


A biomarker, sometimes called a biological marker, is a substance within the body which can be used by researchers as an indicator of normal or abnormal biological processes (which might further indicate the presence or absence of disease or medical problems). Such biomarkers are therefore sometimes objectively measured and evaluated during scientific studies.

Cerebrospinal fluid (CSF)

This is a clear, colourless liquid that circulates throughout the central nervous system. It lies between the brain and the skull and therefore also acts as a kind of shock absorber or cushion, protecting the brain and spinal cord (which are the main parts of the central nervous system) from damage (e.g. in the event of a blow or fall). Another function of CSF is to deliver nutrients and wash away waste materials.


A cohort is a group of people who all experienced a certain period of time together during a particular time span. This does not mean that they necessarily knew each other but simply that they lived through that time. A cohort might therefore be people born between particular dates, people aged between 40 and 50, people who lived through the second world war or people who worked in coal mines between the age of 20 and 40.

Control group

The control group in a clinical trial is the group of participants which does not receive the experimental drug. This does not necessarily mean that they receive nothing or a dummy pill (placebo) as they might receive the standard treatment for their condition. In experimental studies, the control group is not exposed to the experimental intervention. For example, in a study to measure the effects of exercise on memory recall, the control group would not do the exercise but the other group (the experimental group) would.   

Double blind placebo controlled

The participant in a clinical trial, his/her relatives and the researchers are all unaware of which participants are receiving the treatment, the placebo or another intervention.


In the context of dementia research, a gatekeeper is the term used to describe a person who is in a position to facilitate or block researchers’ access to people with dementia who might be willing to take part in a study. An example of a gatekeeper would be the manager of a care home or day care centre.


The hypothesis is the specific question to which researchers want to find an answer. Hypotheses tend to be phrased in specific ways which include a prediction that there will be a relationship between two or more variables and even what the nature of the relationship will be.  This is accompanied by a null hypothesis which basically states that this will not be the case.  Statistical analysis establishes which of the two hypotheses is most likely.

Longitudinal studies

Longitudinal studies are studies which involve the same group of people on more than one occasion (usually several times and often over a fairly long period of time).


The placebo is an inactive intervention. In clinical trials, this may, for example, be a tablet or an injection which looks just like the one taken by other participants who are not in the placebo group but it does not contain the active ingredient.


The term pharmacokinetics comes from two Greek words which mean drug and “to do with motion”. As a science or study, it is about how drugs move through the body covering, for example, how they are absorbed, at what rate and how they are eliminated from the body.


Pharmacodynmics is the study of the effects of drugs. The term describes the biological and physiological effect that a drug has on the body, the mechanisms of the drug action and the relationship between the concentration of the drug and its effect.


“Pharmacogenomics” combines two terms: pharmacology (the science of drugs) and genomics (the study of genes and their functions). It is about how a person’s genes affect the way their body responds to drugs. The aim is to eventually develop drugs which are tailored to each person’s genetic make-up.


Polypharmacy literally means “many drugs” and is the term used to refer to the situation whereby elderly people, in particular, consume a relatively large number of prescription or over-the-counter drugs (i.e. medication, tablets, liquids, medical patches etc.). The number and combination of these drugs may, in some cases, be harmful.


A protocol, in the context of research, is a plan which is drawn up by the researchers and contains all the details of what they will do during a particular study and how they will do it. This typically covers the design of the study, the criteria for the choice of participants, step-by-step details of how the intervention (or review or observation etc.) will be carried out and how the data will be analysed.

Randomised controlled trial

In a randomised controlled trial, people are assigned to different groups (e.g. to the experimental drug group or the placebo group) in a random manner. The principle is similar to tossing a coin but usually this is done with the aid of a computer programme which generates random numbers which can then be used to determine which group each person is assigned to. The main purpose of randomisation is to avoid possible selection bias. It may also be perceived as being fair. 

Retrospective studies

Retrospective studies collect data in the present and linked to the past. For example, a retrospective study might involve asking people about their smoking, drug taking or drinking habits at various stages of their lives.


A sample is a subset of the population. In some studies, particularly quantitative studies, the sample is representative of the population, which means that it shares the same characteristics of the population. This is not always the case or even necessary, particularly, in qualitative studies where selection may be based on other criteria such as theoretical concerns or the desire to obtain a wide range of different responses (e.g. attitudes or perceptions).

Statistical analysis

Statistical analysis is a way of analysing data which permits researchers to state with varying degrees of certainty whether there is a relationship between different variables. Statistical analysis can never prove that a hypothesis is true. It can only provide sufficient evidence to support or refute it.


Variables are the characteristics or attributes that the researchers are interested in and which typically “vary” in two or more categories (e.g. male/female; mild/moderate/severe or on a continuum of score e.g. satisfaction score rated on a scale of 1-5).



Last Updated: Thursday 29 March 2012


  • Acknowledgements

    The above information was published in the 2011 Report "The ethics of dementia research" as part of Alzheimer Europe's 2011 Work Plan which received funding from the European Union in the framework of the Health Programme.
  • European Union