Glossary of OCD terms
A
Adolescence
Adolescence is the transitional phase of life between childhood and adulthood. Although adolescence is usually associated with teenage years, it may start earlier and end later. Adolescence is a stage of physical and psychological development, where patterns of behaviour are established that can shape the person’s health in the future.
Anxiety
Anxiety is a natural human response to uncertain or threatening situations. People with anxiety experience feelings of unease and worried thoughts, as well as sometimes physical sensations, such as increased heartbeat or sweating. Anxiety can be mild or severe and is experienced by everyone at some point in their lives. Yet, some people experience anxiety more often and find it more difficult to control, which can negatively affect the person’s day-to-day life.
B
Behaviour
Behaviour is the way in which an animal or person reacts in response to a particular situation or stimulus. In research, measuring behaviours can be used as a way to examine and understand people and social interactions.
Brain
The brain is the most complex organ in the body. It has over 86 billion brain cells called neurons, which work closely together to form different brain areas. These brain areas talk to each other to exchange information, forming networks within the brain. Different brain areas tend to specialise in one type of information, but because different brain areas communicate and interact, the brain is able to display a wide range of complex behaviours, such as speech, reasoning, or learning.
Brain cell (neuron)
Brain cells, or neurons, are the fundamental units of the nervous system (which includes the brain, the spinal cord and nerves across your body). In order to communicate with other cells, a neuron sends out an electrical signal. This causes the release of brain chemicals called neurotransmitters. These are received by the next cell, which passes the message along. Through a complex network of neurons, information is sent back and forth between the brain and the body, allowing you to move, think, and process everything in your surroundings.
Brain imaging
Brain imaging (or neuroimaging) offers researchers and doctors a view into the structure and function of the brain in a non-invasive way (i.e., without surgery). Many brain imaging techniques are available, including magnetoencephalogram (MEG), electroencephalography (EEG), and (functional) magnetic resonance imaging (MRI).
For more information, see our Imaging Techniques section in OCD Resources.
Brain networks
Brain networks are connected regions of the brain. They can be connected in a structural way (a bit like highways between different brain areas) or in a functional way (i.e., together, they are activated with other areas for the same purpose). These networks work together to perform cognition, like when we are doing a task. Examples of common and stable brain networks include the frontostriatal loops.
C
Cognition
Cognition refers to the mental process taking place in the brain that allows us to acquire knowledge and understanding about the world. Examples of cognitive processes include attention, language, learning, memory and perception.
Cognitive-behavioural therapy (CBT)
Cognitive-behavioural therapy (CBT) refers to a specific form of therapy, in which trained mental health therapists guide the person to alter behaviours and thought patterns. Exposure and Response Prevention (ERP) is the most important type of CBT for people living with OCD, as it directly challenges the OCD cycle of obsessions and compulsions.
For more information, see our Treatments section in OCD Resources.
Compulsions
Compulsions are repetitive behaviours or mental acts that a person feels driven to perform, often in order to get some relief from the anxiety or distress stemming from the obsessions that they experience. Example of compulsions include excessive washing and cleaning, ordering or arranging things in a particular way, repeating a word a certain number of times in your head or repetitive body movements such as tapping or blinking. Compulsions are time-consuming and can become debilitating and get in the way of important daily activities.
For more information, see our Background to OCD section in OCD Resources.
D
Deep Brain Stimulation (DBS)
Deep Brain Stimulation (DBS) involves the placement of electrodes in certain areas of the brain during brain surgery. By sending electrical signals to the brain cells close to it, these electrodes help to regulate abnormal brain activity. Deep brain stimulation is used to treat a number of conditions, including Parkinson's disease, and is sometimes used in very severe and treatment-resistant OCD.
Please note, these methods are currently still being developed, and/or are reserved for people who do not respond to commonly recommended treatments. The availability and approval of DBS and other medications varies between countries and is subject to change.
Disorder
A disorder is an illness that disrupts normal physical or mental daily functioning.
Dopamine
Dopamine is a chemical messenger (or neurotransmitter), that carries messages between brain cells. Dopamine is often known as the “feel good” neurotransmitter because it is involved in the experience of reward, pleasure and motivation. Dopamine is also important in controlling other body functions, including memory, movement or learning. When dopamine levels are too low or too high they can cause problems, such as in Parkinson’s disease and possibly attention-deficit/hyperactivity disorder (ADHD).
E
Electroencephalography (EEG)
Electroencephalography (EEG) is a brain imaging technique which measures electric waves that your brain cells naturally give out as they communicate with each other. In EEG, the electric waves are detected by sensors that are attached close to your head. This allows us to see how brain waves change over time. EEG does not allow us to precisely locate where that activity is coming from, but it can tell us a lot about how information is processed in very fast timescales, e.g. within a few milliseconds. EEG is often used in research to study multiple processes, as well as in clinical settings - for example where it is used to identify disturbances that happen during sleep.
Evidence-based therapy
Evidence-based therapy applies to treatments that are chosen based on the best available research, together with expertise of doctors and healthcare professionals. These treatments have been rigorously tested in clinical trials, and have been proven to have effective outcomes. An example of an evidence-based therapy is Cognitive Behavioural Therapy (CBT).
Exposure and Response Prevention (CBT-ERP)
Exposure and Response Prevention (ERP) is the most important type of Cognitive-Behavioural Therapy (CBT) for people living with OCD, as it directly challenges the OCD cycle of obsessions and compulsions. Here, the person with OCD is put into situations that may normally trigger their OCD symptoms (like compulsions), but then tries to not carry out the compulsive acts. For example, in a person that experiences OCD focused on harm, they might be asked to experience exposures involving their triggers, such as handling sharp objects or looking at a photograph of an accident. With the guidance of the therapist, they confront the situation, embracing the discomfort or anxiety it may cause and resist the urge to engage with compulsive behaviours. By doing this, they learn that the situation itself is not truly threatening and over time the brain learns that it does not always have to react with the same feelings (distress) and behaviours (compulsions) in those specific situations. Therefore, CBT with ERP changes the way that the brain works through the power of talking, learning and practicing changes in behavioural patterns. This approach is often challenging, but highly effective.
For more information, see our Treatments section in OCD Resources.
F
Frontostriatal loops
Frontostriatal loops, or circuits, are pathways in the brain that connect the front part of the brain with a region in the inner part of the brain called the striatum. They are called ‘loops’ because they form a closed-loop system, with one pathway going from the frontal regions to the striatum and another pathway going from the striatum to frontal brain regions. These loops are important in our ability to select and process important information, as well as controlling our behaviour, planning and organisation, or decision-making. They are thought to be particularly important in the selection of appropriate actions and in reinforcement learning, which deals with our ability to learn associations between actions or events and the occurrence of pleasant or unpleasant events.
Changes within the frontostriatal loops have been associated with several neurological and psychiatric disorders, including OCD. The exact role of the frontostriatal loops in these disorders is currently the subject of ongoing research.
G
Genes
A gene is made up of DNA, and is the basic unit that determines which features or characteristics a person inherits from their parents.
M
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) is a brain imaging technique that uses the magnetic properties of the brain tissue to take “pictures” of your brain so that we can see its structure. MRI scanners are large machines with a big magnet at the centre.
Using a particular type of MRI called functional MRI (fMRI), we can also take multiple snapshots of the brain over a period of time to see which brain areas are active when people are performing certain tasks. This means that we can see how the brain reacts to different things, for example, reacting to seeing a spider.
One of the big advantages of MRI is that it can give a very clear picture of how the brain looks, including how different areas are connected to each other, as well as which areas are involved in certain processes. Yet, unlike EEG or MEG, fMRI is not as good as telling us how the brain changes over very short timescales because it takes a bit of time to take a snapshot of the brain.
For more information, see our Imaging Techniques section in OCD Resources.
Magnetoencephalography (MEG)
Magnetoencephalography (MEG) is a brain imaging technique that measures magnetic waves that your brain cells naturally give out when they communicate with each other. In MEG, the magnetic waves are detected by sensors that are attached close to your head in a helmet-like part. This allows us to see how brain waves change over time. MEG can tell us a lot about how information is processed in very fast timescales, e.g. within a few milliseconds. In comparison to EEG, it is also more precise in locating where in the brain the measured activity is coming from. However, MEG is not as precise at locating brain activity as functional MRI.
For more information, see our Imaging Techniques section in OCD Resources.
Mental Illness
Mental illnesses refer to a wide range of conditions that affect your mood, thinking and behaviour. While they can vary in their severity (ranging from mild to severe), these conditions are usually associated with distress or impairment in important areas of functioning. In severe cases, they can substantially interfere with one or several life activities. Examples of mental illnesses include depression, anxiety disorders, schizophrenia, eating disorders and OCD.
If you are dealing with mental illness, you can find support links in our OCD Resources section.
N
Neuroscientist
Neuroscientists are researchers who study the nervous system, including the brain. They are not only interested in how the nervous system works in healthy people, but also what happens when people experience different neurological, psychiatric and neurodevelopmental disorders.
Neuroscience is an area of research that brings together different types of knowledge, such as biochemistry, psychology, molecular biology, neurobiology, mathematics and computation. Neuroscientists use different tools and methods, ranging from animal research to human brain imaging to provide answers to their specific questions.
Neurotransmitters
Neurotransmitters are chemical messengers used by the nervous system (which includes the brain, the spinal cord and nerves across your body). They transmit messages between neurons (brain cells), or from neurons to muscles. Neurotransmitters have several functions, including regulating mood, appetite and sleep and are therefore extremely important for the body to function properly. Examples of neurotransmitters include serotonin and dopamine.
O
Obsessions
Obsessions are unwanted thoughts, images, doubts or urges that enter a person’s mind over and over again and feel outside of the person’s control. Their repetitive and intrusive nature can cause feelings of anxiety, fear or disgust. Obsessions can include excessive worrying of potential negative consequences of an action or feeling overly responsible for something terrible happening. Obsessions are debilitating, time-consuming and negatively interfere with the daily activities of the person.
For more information, see our Background to OCD section in OCD Resources.
Obsessive-Compulsive Disorder (OCD)
Obsessive-Compulsive Disorder (OCD) is a mental illness in which a person experiences unwanted, intrusive and repetitive thoughts (obsessions), engages in repetitive behaviours or mental acts (compulsions), or both. These symptoms are time-consuming, debilitating and can cause significant distress and interfere with daily life.
For more information, see our Background to OCD section in OCD Resources.
OCD trigger
A trigger is something that "sets off" or causes a person to experience an obsession. Triggers can be external, such as an event or object, or internal, such as a thought or sensation.
P
Pacemaker
The heart is like a pump and is controlled by electrical signals. In some conditions, the beating of the heart can be off, causing it to beat too quickly, too slowly or with an irregular rhythm. A pacemaker is a small device that is generally placed under the skin on the left side of the chest. This device sends electrical impulses to the heart, controlling the speed at which it beats. People with pacemakers may need to avoid certain electrical devices or devices that have strong magnetic fields, like MRI scanners.
Plasticity
Brain plasticity (or neuroplasticity) refers to the lifelong ability of the brain to change in response to internal or external events. For example, when we learn new skills or memorize new things, this causes long lasting changes in how your brain works. The way that the brain achieves this is by making structural changes like growing new cells or connections, or rewiring existing connections. The brain can also change the function of certain brain cells. For example, in blind people, the visual cortex may change its function to help to process information from our other senses, like touch or hearing.
Prefrontal cortex
The prefrontal cortex is the area of the brain that lies directly behind the eyes and the forehead. The brain does not reach full maturity until the mid-to-late 20s and the prefrontal cortex is one of the last parts to mature. It can be divided into different areas based on their structure and function. These include the dorsolateral prefrontal cortex, the ventromedial prefrontal cortex and the orbitofrontal cortex. Each of these regions contribute to how we perceive the world and how we act in it. Through its interactions with other regions of the brain, the prefrontal cortex is thought to contribute a great deal to making us who we are as individuals.
Psychotherapist
A psychotherapist, uses psychotherapy approaches to help people to manage emotional, behavioural and mental health issues. In the UK, psychotherapists need to undergo appropriate and recognized training to become officially certified. In the US, psychotherapists can have doctoral (e.g. PhD, PsyD, EdD) or masters (e.g. MSW, MA, MS) degrees, and are required to be independently licensed as a psychologist, social worker, counsellor, etc. before they can see clients on their own. Please note, training and terminology of these professionals may vary between countries, and may be subject to change.
S
Serotonin
Serotonin is a chemical messenger, or neurotransmitter, that carries messages between nerve cells in the brain and throughout your body. It plays an important role in various brain and body functions, such as in mood regulation, learning, memory, sleep or digestion. When serotonin levels are too low or too high they can cause physical and psychological health problems, such as depression and anxiety.
Striatum
The striatum is a structure found in the most inner part of the brain. The striatum plays several important roles, including facilitating the experience of pleasure, aiding in learning, and planning and executing actions. Notably, it is recognised as the brain part that links pleasant or unpleasant experiences to events or actions, so that we learn whether it is appropriate to avoid or approach these scenarios, or to do or withhold certain actions. As such, the striatum is involved in disorders such as OCD.
Symptom
A symptom is a physical or mental feature that a person experiences, which indicates the presence of a disorder. Examples of symptoms include headaches, difficulty falling asleep, low mood, runny nose or cough. They are used by doctors to help to determine the underlying disorder.
T
Tasks
Tasks, also known as psychological tasks, behavioural tasks or experiments, are developed to answer questions about a specific behavioural and/or cognitive process.
For instance, if researchers want to study how people make decisions and how much information they gather before making decisions, they can use an information sampling tasks. These tasks involve participants uncovering as much information as they choose, which is then quantified, before making a decision. These behaviours and quantified mechanisms can then also be compared across groups, such as people with and without OCD.
At the same time, researchers might also measure other things such as brain activity or eye movements to learn more about the process they are investigating. While there are many established tasks that have been used for several years to study specific cognitive processes, researchers also continue to develop new and more interactive tasks that allow studying new processes and/or offer new perspectives by measuring different and more complex behaviours. One example that offers the potential of measuring more complex behaviours is the use of games that have the additional advantage of being more engaging.
For more information, see our OCD Research Behind this Project and Get Involved in Research sections in OCD Resources.
Transcranial magnetic Stimulation (TMS)
Transcranial Magnetic Stimulation is a non-invasive brain stimulation technique. It temporarily changes brain activity by using magnetic fields. Because the brain works a bit like a wire by sending electric signals from one neuron to the next, the brain areas that are close to the coil are influenced by the magnetic field. This can trigger a change in their activity.
TMS is used in research in order to understand which regions are important during the performance of a certain function and also by doctors as a treatment for certain diseases.
Please note, these methods are still currently being developed, and/or are reserved for people who do not respond to commonly recommended treatments. The availability and approval of TMS and other medications varies between countries and is subject to change.
V
Visual cortex
The visual cortex is the part of the brain that processes visual information. It is located at the back of the brain. Visual information from the eyes travels through other parts of the brain before reaching the visual cortex. The areas of the visual cortex communicate back and forth with each other and also with other areas outside the visual cortex in order to provide us with a complete picture of what we are seeing.