The Science of Mental Illness

accrued deficits: The delays or lack of development in emotional, social, academic, or behavioral skills that a child or adolescent experiences because of untreated mental illness. The mental illness keeps the individual from developing these life skills at the usual stage of life. An individual may never fully make up for these deficiencies.

acute: Refers to a disease or condition that has a rapid onset, marked intensity, and short duration.

antidepressant: A medication used to treat depression.

anxiety: An abnormal sense of fear, nervousness, and apprehension about something that might happen in the future.

anxiety disorder: Any of a group of illnesses that fill people’s lives with overwhelming anxieties and fears that are chronic and unremitting. Anxiety disorders include panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, phobias, and generalized anxiety disorder.

attention deficit disorder (ADD): See attention deficit hyperactivity disorder.

attention deficit hyperactivity disorder (ADHD): A mental illness characterized by an impaired ability to regulate activity level (hyperactivity), attend to tasks (inattention), and inhibit behavior (impulsivity). For a diagnosis of ADHD, the behaviors must appear before an individual reaches age seven, continue for at least six months, be more frequent than in other children of the same age, and cause impairment in at least two areas of life (school, home, work, or social function).

autism: A developmental brain disorder that typically affects a person’s ability to communicate, engage in social interactions, and respond appropriately to the environment. Some people with autism have few problems with learning and speech, and are able to function well in society. Others may be significantly impaired or have serious language delays. Autism makes some people seem closed off and shut down; others seem locked into repetitive behaviors and rigid patterns of thinking.

axon: The long, fiberlike part of a neuron by which the cell carries information to target cells.

bipolar disorder: A depressive disorder in which a person alternates between episodes of major depression and mania (periods of abnormally and persistently elevated mood). Also referred to as manic-depression.

cerebrum: The upper part of the brain that consists of the left and right hemispheres.

chronic: Refers to a disease or condition that persists over a long period of time.

cognition: Conscious mental activity that informs a person about his or her environment. Cognitive actions include perceiving, thinking, reasoning, judging, problem solving, and remembering.

conduct disorder: A personality disorder of children and adolescents involving persistent antisocial behavior. Individuals with conduct disorder frequently participate in activities such as stealing, lying, truancy, vandalism, and substance abuse.

delusion: A false belief that persists even when a person has evidence that the belief is not true.

dendrite: The specialized fibers that extend from a neuron’s cell body and receive messages from other neurons.

depression (depressive disorders): A group of diseases including major depressive disorder (commonly referred to as depression), dysthymia, and bipolar disorder (manic-depression). See bipolar disorder, dysthymia, and major depressive disorder.

Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV): A book published by the American Psychiatric Association that gives general descriptions and characteristic symptoms of different mental illnesses. Physicians and other mental health professionals use the DSM-IV to confirm diagnoses for mental illnesses.

disease: A synonym for illness. See illness.

disorder: An abnormality in mental or physical health. In this module, disorder is used as a synonym for illness.

dysthymia: A depressive disorder that is less severe than major depressive disorder but is more persistent. In children and adolescents, dysthymia lasts for an average of four years.

electroconvulsive therapy (ECT): A treatment for severe depression that is usually used only when people do not respond to medications and psychotherapy. ECT involves passing a low-voltage electric current through the brain. The person is under anesthesia at the time of treatment. ECT is not commonly used in children and adolescents.

electroencephalography (EEG): A method of recording the electrical activity in the brain through electrodes attached to the scalp.

electroshock therapy: See electroconvulsive therapy.

frontal lobe: One of the four divisions of each cerebral hemisphere. The frontal lobe is important for controlling movement and associating the functions of other cortical areas.

gray matter: The portion of brain tissue that is dark in color. The gray matter consists primarily of nerve cell bodies, dendrites, and axon endings.

hallucination: The perception of something, such as a sound or visual image, that is not actually present other than in the mind.

hypothalamus: The part of the brain that controls several body functions, including feeding, breathing, drinking, temperature, and the release of many hormones.

illness: A problem in which some part or parts of the body do not function normally, in a way that interferes with a person’s life. For the purpose of this module, other terms considered to be synonyms for illness include disease, disorder, condition, and syndrome.

magnetic resonance imaging (MRI): An imaging technique that uses magnetic fields to take pictures of the structure of the brain.

major depressive disorder: A depressive disorder commonly referred to as depression. Depression is more than simply being sad; to be diagnosed with depression, a person must have five or more characteristic symptoms nearly every day for a two-week period.

mania: Feelings of intense mental and physical hyperactivity, elevated mood, and agitation.

manic-depression: See bipolar disorder.

mental illness: A health condition that changes a person’s thinking, feelings, or behavior (or all three) and that causes the person distress and difficulty in functioning.

mental retardation: A condition in which a person has an IQ that is below average and that affects an individual’s learning, behavior, and development. This condition is present from birth.

myelin: A fatty material that surrounds and insulates the axons of some neurons.

neuron (nerve cell): A unique type of cell found in the brain and body that processes and transmits information.

neurosis: A term no longer used medically as a diagnosis for a relatively mild mental or emotional disorder that may involve anxiety or phobias but does not involve losing touch with reality.

neurotransmission: The process that occurs when a neuron releases neurotransmitters that relay a signal to another neuron across the synapse.

neurotransmitter: A chemical produced by neurons that carries messages to other neurons.

obsessive-compulsive disorder (OCD): An anxiety disorder in which a person experiences recurrent unwanted thoughts or rituals that the individual cannot control. A person who has OCD may be plagued by persistent, unwelcome thoughts or images or by the urgent need to engage in certain rituals, such as hand washing or checking.

oppositional defiant disorder: A disruptive pattern of behavior of children and adolescents that is characterized by defiant, disobedient, and hostile behaviors directed toward adults in positions of authority. The behavior pattern must persist for at least six months.

panic disorder: An anxiety disorder in which people have feelings of terror, rapid heart beat, and rapid breathing that strike suddenly and repeatedly with no warning. A person who has panic disorder cannot predict when an attack will occur and may develop intense anxiety between episodes, worrying when and where the next one will strike.

phobia: An intense fear of something that poses little or no actual danger. Examples of phobias include fear of closed-in places, heights, escalators, tunnels, highway driving, water, flying, dogs, and injuries involving blood.

pituitary gland: An endocrine organ closely linked with the hypothalamus. The pituitary secretes a number of hormones that regulate the activity of other endocrine organs in the human body.

positron: A positively charged particle that has the same mass and spin as—but the opposite charge of—an electron.

positron emission tomography (PET): An imaging technique for measuring brain function in living subjects by detecting the location and concentration of small amounts of radioactive chemicals.

postsynaptic neuron: The neuron that receives messages from other neurons.

presynaptic neuron: The neuron that sends messages to other neurons by releasing neurotransmitters into the synapse.

psychiatrist: A medical doctor (M.D.) who specializes in treating mental diseases. A psychiatrist evaluates a person’s mental health along with his or her physical health and can prescribe medications.

psychiatry: The branch of medicine that deals with identifying, studying, and treating mental, emotional, and behavioral disorders.

psychologist: A mental health professional who has received specialized training in the study of the mind and emotions. A psychologist usually has an advanced degree such as a Ph.D.

psychosis: A serious mental disorder in which a person loses contact with reality and experiences hallucinations or delusions.

psychotherapy: A treatment method for mental illness in which a mental health professional (psychiatrist, psychologist, counselor) and a patient discuss problems and feelings to find solutions. Psychotherapy can help individuals change their thought or behavior patterns or understand how past experiences affect current behaviors.

receptor: A molecule that recognizes specific chemicals, including neurotransmitters and hormones, and transmits the message into the cell on which the receptor resides.

relapse: The reoccurrence of symptoms of a disease.

reuptake pump: The large molecule that carries neurotransmitter molecules back into the presynaptic neuron from which they were released. Also referred to as a transporter.

risk: The chance or possibility of experiencing harm or loss.

risk factor: Something that increases a person’s risk or susceptibility to harm.

schizophrenia: A chronic, severe, and disabling brain disease. People with schizophrenia often suffer terrifying symptoms such as hearing internal voices or believing that other people are reading their minds, controlling their thoughts, or plotting to harm them. These symptoms may leave them fearful and withdrawn. Their speech and behavior can be so disorganized that they may be incomprehensible or frightening to others.

selective serotonin reuptake inhibitors (SSRIs): A group of medications used to treat depression. These medications cause an increase in the amount of the neurotransmitter serotonin in the brain.

serotonin: A neurotransmitter that regulates many functions, including mood, appetite, and sensory perception.

single photon emission computed tomography (SPECT): A brain imaging process that measures the emission of single photons of a given energy from radioactive tracers in the human body.

stigma: A negative stereotype about a group of people.

St. John’s wort: An herb sometimes used to treat mild cases of depression. Although the popular media have reported successes using St. John’s wort, it is not a recommended treatment. The scientific evidence for its effectiveness and safety is not conclusive.

symptom: Something that indicates the presence of a disease.

synapse: The site where presynaptic and postsynaptic neurons communicate with each other.

synaptic space: The intercellular space between a presynaptic and postsynaptic neuron. Also referred to as the synaptic cleft.

syndrome: A group of symptoms or signs that are characteristic of a disease. In this module, the word syndrome is used as a synonym for illness.

transporter: A large protein on the cell membrane of axon terminals. It removes neurotransmitter molecules from the synaptic space by carrying them back into the axon terminal that released them. Also referred to as the reuptake pump.

ventricle: One of the cavities or spaces in the brain that are filled with cerebrospinal fluid.

vesicle: A membranous sac within an axon terminal that stores and releases neurotransmitters.