Antidepressant Medication. Since the 1960s antidepressant drugs have been a popular treatment for major depression. There are four classes of antidepressant medications: Tricyclic Antidepressants (TCAs); Monoamine Oxidase Inhibitors (MAOIs); Selective Serotonin Reuptake Inhibitors (SSRIs) and “atypical antidepressants” which include other mechanisms of action.

Anxiety Disorders. Anxiety disorders are a group of emotional illnesses including phobias, panic attacks, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD) and post-traumatic stress disorder.

Bipolar Disorder. Commonly known as manic depressive illness, bipolar disorder involves mood swings from “high” episodes of mania to periods of depression. Between episodes, the people with bipolar disorder often experience the normal range of moods. Manic episodes are distinguished by feelings of euphoric happiness, irritability and high levels of energy.

Cognitive Behavioral Therapy (CBT). According to proponents of this psychotherapy approach, how you feel is the result of how you think. Cognitive therapists help patients identify distorted or negative ways of thinking and replace them with more positive perceptions. Depression is relieved by altering an unrealistically negative view of ones self and the world. People with major depression or anxiety disorders may benefit most from CBT according to The Journal of Rational-Emotive & Cognitive-Behavior Therapy.

Chronic or Recurrent Depression. A major depressive episode that is of at least two years in duration is called chronic depression. When multiple depressive episodes occur over time, this is called recurrent depression.

Cingulotomy. A surgical technique that interrupts the cingulate gyrus, a bundle of nerve fibers in the front of the brain, by applying heat or cold. This procedure has been used to treat obsessive compulsive disorder.

Clinical Depression. Emotional experiences of sadness, loss or mood states that are persistent and can interfere significantly with an individual’s ability to function.

Major Depression. A severe form of depression characterized by having five or more symptoms of depression (as defined by DSM IV) during the same two week period. Symptoms include intense sadness, feelings of hopelessness, a sudden change in appetite or weight and a loss of pleasure and interest in normal activities.

Major Depressive Disorder. Mood disorder characterized by one or more episodes of major depression.

Dysthymic Disorder (formerly known as Dysthymia). A long lasting, persistent, mild depression lasting at least two years, often accompanied by major depressive episodes.

Electroconvulsive Therapy (ECT). A treatment usually for the symptoms of severe and/or psychotic depression, ECT is the application of an electrical current through electrodes applied to the patient’s head to induce a seizure. ECT is performed under anesthesia and the amount of electricity needed to induce a seizure varies considerably from patient to patient. The treatments are repeated two or three times per week until clinical improvements are achieved. Typical courses of ECT are six to ten treatments. Relapse rates are high, and many patients experience memory impairment.

Failed Adequate Treatment. Failure to respond to electroconvulsive therapy or an established antidepressant drug administered at an adequate dose for an adequate duration.

General Anesthesia. General Anesthesia is a treatment with certain medicines usually administered by an anesthesiologist or nurse anesthetist that puts you into a deep sleep so you do not feel any discomfort during surgery. (adapted from the NIH medical encyclopedia)

Interpersonal Therapy (IPT). Short-term therapy that concentrates on relationships as the key to understanding and overcoming emotional difficulties. The overall goal of IPT is to relieve symptoms of depression, improve self-esteem and help patients get what they want or need from relationships in a positive way. The bond that the client develops with the therapist is a crucial component of this therapy.

Mania. An acute mood characterized by euphoria, a sense of well-being and an increase in activity level. One of the two mood cycles experienced in bipolar disorder.

Manic Depression or Manic Depressive Illness. See Bipolar Disorder

Major Depressive Episode. Meets the criteria for being in a current episode of major depression.

Neurotransmitters. Chemicals used by brain cells to communicate.

Norepinephrine. Norepinephrine is a catecholamine with multiple roles including as a hormone and a neurotransmitter. One of the most important functions of norepinephrine is its role as the neurotransmitter released from the sympathetic neurons to affect the heart. As a stress hormone, norepinephrine affects parts of the brain, such as the amygdala, where attention and responses are controlled. Along with epinephrine, norepinephrine also underlies the fight-or-flight response, directly increasing heart rate, triggering the release of glucose from energy stores, and increasing blood flow to skeletal muscle. It increases the brain's oxygen supply. Norepinephrine can also suppress neuroinflammation when released diffusely in the brain from the locus coeruleus. Norepinephrine is also called noradrenaline.

Psychiatrists. Licensed medical doctors who specialize in diagnosing and treating mental illness. They provide counseling and can prescribe medications.

Psychologists. Psychologists may have a Ph.D. in psychology or a Psy.D. (doctorate in clinical psychology). However, they do not study medicine and cannot prescribe medication.

Psychotherapy. The treatment of emotional or mental disorders by counseling. Most mental health professionals tailor their approach to the needs, problems and personality of the person seeking help, and they may combine different techniques in the course of therapy. Many individuals are turning to short-term psychotherapy which may last several weeks to several months. Most likely to benefit are those interested in solving an immediate problem.

Pulse Generator. VNS Therapy device implanted in the patient’s chest; holds the battery and delivers stimulation to the vagus nerve through the VNS Therapy Lead (from Patient’s Manual-epilepsy)

Remission. Remission is defined as the absence of depressive symptoms and the return of psychosocial functioning for at least six months. Patients with depression who achieve remission no longer meet the criteria for major depression.

Response. Response is defined as at least a 50 percent reduction in the Hamilton Rating Scale for Depression (HAM-D) scores. Response may be a partial improvement in symptoms rather than a state of being completely symptom-free.

Selective Serotonin Reuptake Inhibitors (SSRIs). Medications, such as fluoxetine (Prozac), sertaline (Zoloft) and paroxetine (Paxil), which alter brain chemistry and relieve depressive symptoms by affecting the neurotransmitter serotonin. These drugs can be used in conjunction with psychotherapy or as the primary treatment.

Treatment-resistant Depression (TRD). While definitions of treatment-resistant depression may differ, most psychiatrists agree that treatment-resistant depression is a major depressive episode that has not had an adequate response to at least two classes of adequate antidepressants at appropriate dose and duration. At least 20 percent of all patients with major depression may experience treatment-resistant depression.

Unipolar Major Depression. A person who has five or more depression symptoms (as defined by DSM IV) and experiences impairment in usual functioning nearly every day during the same two-week period. It typically occurs in discrete episodes that happen over a person’s lifetime.

Vagus Nerve. The tenth cranial nerve. A mixed nerve that has both motor and sensory function.

Vagus Nerve Stimulation (VNS) Therapy System. VNS Therapy is approved for the adjunctive long-term treatment of chronic or recurrent depression for patients 18 years of age or older who are experiencing a major depressive episode and have not had an adequate response to four or more adequate antidepressant treatments. VNS Therapy consists of an implanted pacemaker-like device that delivers mild, intermittent pulses that are sent to the vagus nerve, which then modulate activity in various areas of the brain thought to be involved in mood regulation. The VNS Therapy System is at various levels of investigational clinical study as a potential treatment for anxiety disorders, Alzheimer’s disease, chronic headache/migraine and bulimia.


The VNS Therapy System is indicated for use as an adjunctive therapy in reducing the frequency of seizures in adults and adolescents over 12 years of age with partial onset seizures, which are refractory to antiepileptic medications.

VNS Therapy (or the VNS Therapy System) is indicated for the adjunctive long-term treatment of chronic or recurrent depression for patients over the age of 18 who are experiencing a major depressive episode and have not had an adequate response to four or more adequate antidepressant treatments.