Category: H

Intracellular aggregates of actin and actin-associated proteins, often occurring as rod shapes in the neurons of individuals affected with certain neurodegenerative disorders, such as alzheimer’s disease and creutzfeldt-jakob disease. Hirano bodies are frequently seen in hippocampal pyramidal cells. Intracellular aggregates of actin and actin-associated proteins, often occurring as rod shapes in the neurons of individuals…

Actions that put one in danger or render one vulnerable to harmful consequences. Needle sharing by addicted persons, for example, is high-risk behavior because of the likelihood of transmission of human immunodeficiency virus (HIV) or other pathogens. Also called risk behavior. In epidemiology, a term used to describe certain activities that increase the risk of…

A major metabolite of serotonin, a biogenic amine found in the brain and other organs. Functional deficits of serotonin in the central nervous system (CNS) have been implicated in suicide and impulsivity and certain types of major mood disorders.  

Family, adoption, and twin studies demonstrate that genetic factors have an important role in certain psychiatric disorders, including schizophrenia, major depressive disorder, and bipolar disorder. The heritability of many psychiatric disorders is high compared with that of other complex disorders such as asthma, diabetes, and stroke. While heritability estimates are high, environmental factors are also…

A very rare movement disorder characterized by involuntary flinging motions of the extremities, whose effects can sometimes be severe enough to prevent patients from being able to perform daily functions. It is usually associated with structural brain lesions but can occur with metabolic abnormalities. The symptoms can also decrease while the patient is asleep, unlike…

Actual or self-perceived inability to act on one’s own behalf; inefficiency in making an impact on one’s environment to create change. A construct referring to the sense of having no control over important events, considered by many theorists to play a central role in anxiety and depression learned helplessness. A feeling of dependence, powerlessness, defenselessness,…

Pleasure-seeking behavior. Contrast with anhedonia. The doctrine that pleasure or happiness is the highest good. The pursuit of pleasure or the gratification of the senses as a primary goal of ethical living.  

A subtype of schizophrenia characterized especially by incoherence, delusions lacking an underlying theme, and affect that is usually flat or inappropriate. Also known as disorganized schizophrenia. Disorganized schizophrenia hebephrenic reaction. A condition in which someone, usually an adolescent, has hallucinations, delusions and deterioration of personality, talks rapidly and generally acts in a strange manner. Form…