a progressive neurodegenerative disease caused by the death of dopamine-producing neurons in the pars compacta region of the substantia nigra of the brain, which controls balance and coordinates muscle movement.

in DSM–IV–TR, an anxiety disorder characterized by recurrent, unexpected panic attacks that are associated with (a) persistent concern about having another attack, (b) worry about the possible consequences of the attacks, (c) significant change in behavior related to the attacks (e.g., avoiding situations, engaging in safety behavior, not going out alone), or (d) a combination of any or all of these.

in DSM–IV–TR, a behavior disorder of childhood characterized by recurrent disobedient, negativistic, or hostile behavior toward authority figures that is more pronounced than usually seen in children of similar age and lasts for at least 6 months.

in DSM–IV–TR and DSM–5, a personality disorder characterized by an extreme need for perfection, an excessive orderliness, an inability to compromise, and an exaggerated sense of moral responsibility (see scrupulosity).

a disorder characterized by recurrent intrusive thoughts (obsessions) that prompt the performance of neutralizing rituals (compulsions).

in DSM–IV–TR and DSM–5, a sleep disorder characterized by the repeated occurrence of frightening dreams that lead to awakenings from sleep.

in DSM–IV–TR and DSM–5, a personality disorder with the following characteristics: (a) a long-standing pattern of grandiose self-importance and an exaggerated sense of talent and achievements; (b) fantasies of unlimited sex, power, brilliance, or beauty; (c) an exhibitionistic need for attention and admiration; (d) either cool indifference or feelings of rage, humiliation, or emptiness as a response to criticism, indifference, or defeat; and (e) various interpersonal disturbances, such as feeling entitled to special favors, taking advantage of others, and inability to empathize with the feelings of others.

n. any disease or disorder of the muscles, hereditary or acquired. The term is usually qualified by an adjective that specifies the type of myopathy or its cause.

Muscle weakness or myasthenia (my- from Greek μυο meaning "muscle" + -asthenia ἀσθένεια meaning "weakness") is a lack of muscle strength. The causes are many and can be divided into conditions that have either true or perceived muscle weakness. 

any abnormality in motor processes, relating primarily to posture, coordination, or locomotion. See also medication-induced movement disorder.

a period characterized by elevated, expansive, or irritable mood, often with several of the following symptoms: an increase in activity or psychomotor agitation; talkativeness or pressured speech; flight of ideas or racing thoughts; inflated self-esteem or grandiosity; a decreased need for sleep; extreme distractibility; and intense pursuit of activities that are likely to have unfortunate consequences (e.g., buying sprees, sexual indiscretions).

in DSM–IV–TR and DSM–5, a mood disorder characterized by persistent sadness and other symptoms of a major depressive episode but without accompanying episodes of mania or hypomania or mixed episodes of depressive and manic or hypomanic symptoms. Also called major depression.

in DSM–IV–TR and DSM–5, a mood disorder characterized by persistent sadness and other symptoms of a major depressive episode but without accompanying episodes of mania or hypomania or mixed episodes of depressive and manic or hypomanic symptoms. 

in DSM–IV–TR, any neurologically based information-processing disorder characterized by achievement that is substantially below that expected for the age, education, and intelligence of the individual, as measured by standardized tests in reading and mathematics and written material. 

see speech and language disorder.