Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introduced by a group of US clinicians in the mid-1970s, the term was adopted by the American Psychiatric Association for this symptom cluster under mood disorders in the 1980 version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), and has become widely used since.
Maprotiline, sold under the brand name Ludiomil among others, is a tetracyclic antidepressant (TeCA) that is used in the treatment of depression. It may alternatively be classified as a tricyclic antidepressant (TCA), specifically a secondary amine. In terms of its chemistry and pharmacology, maprotiline is closely related to such-other secondary-amine TCAs as nortriptyline and protriptyline and has similar effects to them, albeit with more distinct anxiolytic effects. Additionally, whereas protriptyline tends to be somewhat more stimulating and in any case is distinctly more-or-less non-sedating, mild degrees of sedation may be experienced with maprotiline.
Depression is a mental state of low mood and aversion to activity. It affects more than 280 million people of all ages. Depression affects a person's thoughts, behavior, feelings, and sense of well-being. Depressed people often experience loss of motivation or interest in, or reduced pleasure or joy from, experiences that would normally bring them pleasure or joy. Depressed mood is a symptom of some mood disorders such as major depressive disorder and dysthymia; it is a normal temporary reaction to life events, such as the loss of a loved one; and it is also a symptom of some physical diseases and a side effect of some drugs and medical treatments. It may feature sadness, difficulty in thinking and concentration and a significant increase or decrease in appetite and time spent sleeping. People experiencing depression may have feelings of dejection or hopelessness and may experience suicidal thoughts. It can either be short term or long term.
Dysthymia, also known as persistent depressive disorder (PDD), is a mental and behavioral disorder, specifically a disorder primarily of mood, consisting of similar cognitive and physical problems as major depressive disorder, but with longer-lasting symptoms. The concept was used by Robert Spitzer as a replacement for the term "depressive personality" in the late 1970s.
Biological psychiatry or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system. It is interdisciplinary in its approach and draws on sciences such as neuroscience, psychopharmacology, biochemistry, genetics, epigenetics and physiology to investigate the biological bases of behavior and psychopathology. Biopsychiatry is the branch of medicine which deals with the study of the biological function of the nervous system in mental disorders.
Atypical depression is defined in the DSM-IV as depression that shares many of the typical symptoms of major depressive disorder or dysthymia but is characterized by improved mood in response to positive events. In contrast to those with atypical depression, people with melancholic depression generally do not experience an improved mood in response to normally pleasurable events. Atypical depression also often features significant weight gain or an increased appetite, hypersomnia, a heavy sensation in the limbs, and interpersonal rejection sensitivity that results in significant social or occupational impairment.
Suicidal ideation, or suicidal thoughts, is the thought process of having ideas, or ruminations about the possibility of completing suicide. It is not a diagnosis but is a symptom of some mental disorders, use of certain psychoactive drugs, and can also occur in response to adverse life events without the presence of a mental disorder.
The behavioural despair test is a test, centered on a rodent's response to the threat of drowning, whose result has been interpreted as measuring susceptibility to negative mood. It is commonly used to measure the effectiveness of antidepressants, although significant criticisms of its interpretation have been made.
Histone deacetylase inhibitors are chemical compounds that inhibit histone deacetylases. Since deacetylation of histones produces transcriptionally silenced euchromatin, HDIs can render chromatin more transcriptionally active and induce epigenomic changes.
Major depressive disorder, often simply referred to as depression, is a mental disorder characterized by prolonged unhappiness or irritability. It is accompanied by a constellation of somatic and cognitive signs and symptoms such as fatigue, apathy, sleep problems, loss of appetite, loss of engagement, low self-regard/worthlessness, difficulty concentrating or indecisiveness, or recurrent thoughts of death or suicide.
Animal models of depression are research tools used to investigate depression and action of antidepressants as a simulation to investigate the symptomatology and pathophysiology of depressive illness or used to screen novel antidepressants. These models provide insights into molecular, genetic, and epigenetic factors associated with depression. Criteria for valid animal models include face, construct, and predictive validity. Endophenotypes, such as anhedonia, behavioral despair, changes in appetite, neuroanatomical alterations, neuroendocrine disturbances, alterations in sleep architecture, and anxiety-related behaviors, are evaluated in these models. Antidepressant screening tests are employed to assess the effects of genetic, pharmacological, or environmental manipulations. Stress models, including learned helplessness, chronic mild stress, and social defeat stress, simulate the impact of stressors on depression. Early life stress models, psychostimulant withdrawal models, olfactory bulbectomy, and genetically engineered mice contribute to a comprehensive understanding of depression's etiology and potential therapeutic interventions.
Developed by Calvin S. Hall, the open field test is an experimental test used to assay general locomotor activity levels, anxiety, and willingness to explore in animals in scientific research. However, the extent to which behavior in the open field measures anxiety is controversial. The open field test can be used to assess memory by evaluating the ability of the animal to recognize a stimuli or object. Another animal test that is used to assess memory using that same concept is the novel object recognition test.
The pharmacology of antidepressants is not entirely clear. The earliest and probably most widely accepted scientific theory of antidepressant action is the monoamine hypothesis, which states that depression is due to an imbalance of the monoamine neurotransmitters. It was originally proposed based on the observation that certain hydrazine anti-tuberculosis agents produce antidepressant effects, which was later linked to their inhibitory effects on monoamine oxidase, the enzyme that catalyses the breakdown of the monoamine neurotransmitters. All currently marketed antidepressants have the monoamine hypothesis as their theoretical basis, with the possible exception of agomelatine which acts on a dual melatonergic-serotonergic pathway. Despite the success of the monoamine hypothesis it has a number of limitations: for one, all monoaminergic antidepressants have a delayed onset of action of at least a week; and secondly, there are a sizeable portion (>40%) of depressed patients that do not adequately respond to monoaminergic antidepressants. Further evidence to the contrary of the monoamine hypothesis are the recent findings that a single intravenous infusion with ketamine, an antagonist of the NMDA receptor — a type of glutamate receptor — produces rapid, robust and sustained antidepressant effects. Monoamine precursor depletion also fails to alter mood. To overcome these flaws with the monoamine hypothesis a number of alternative hypotheses have been proposed, including the glutamate, neurogenic, epigenetic, cortisol hypersecretion and inflammatory hypotheses. Another hypothesis that has been proposed which would explain the delay is the hypothesis that monoamines don't directly influence mood, but influence emotional perception biases.
Bacteriotherapy is the purposeful use of bacteria or their products in treating an illness. Forms of bacteriotherapy include the use of probiotics, microorganisms that provide health benefits when consumed; fecal matter transplants (FMT) /intestinal microbiota transplant (IMT), the transfer of gut microorganisms from the fecal matter of healthy donors to recipient patients to restore microbiota; or synbiotics which combine prebiotics, indigestible ingredients that promote growth of beneficial microorganisms, and probiotics. Through these methods, the gut microbiota, the community of 300-500 microorganism species that live in the digestive tract of animals aiding in digestion, energy storage, immune function and protection against pathogens, can be recolonized with favorable bacteria, which in turn has therapeutic effects.
Buprenorphine/samidorphan is a combination formulation of buprenorphine and samidorphan which is under development as an add on to antidepressants in treatment-resistant depression (TRD).
Epigenetics of depression is the study of how epigenetics contribute to depression.
Marble burying is an animal model used in scientific research to depict anxiety or obsessive–compulsive disorder (OCD) behavior. It is based on the observation that rats and mice will bury either harmful or harmless objects in their bedding. While widely used there is significant controversy over the interpretation of its results.
The light-dark box test (LDB) is a popular animal model used in pharmacology to assay unconditioned anxiety responses in rodents. The extent to which behavior in the LDB measures anxiety is controversial.
The Vogel conflict test (VCT) is a conflict based experimental method primarily used in pharmacology. It is used to determine anxiolytic properties of drugs. The VCT predicts drugs that can manage generalized anxiety disorders and acute anxiety states.
Immuno-psychiatry, according to Pariante, is a discipline that studies the connection between the brain and the immune system. It differs from psychoneuroimmunology by postulating that behaviors and emotions are governed by peripheral immune mechanisms. Depression, for instance, is seen as malfunctioning of the immune system.
