A situation of confusion, lack of organization, or messiness: Alison realized that she could not work productively with the disorder on her desk; so, each day before going home, she tidied up her working area.

A severe pervasive developmental disorder which usually takes place before three years of age and a biological basis related to neurologic or neurophysiologic factors: An autistic disorder is characterized by qualitative impairment in reciprocal social interactions; such as, a lack of awareness of the existence of feelings of others, failure to seek comfort at times of distress, and of verbal and nonverbal communication.

Other characteristics of autistic disorders sometimes include cognitive impairment, "hyperactivitiy" or "hyporeactivity" to certain stimuli, stereotypic behaviors, neurological abnormalities; such as, seizures or altered muscle tone, sleeping or eating pattern abnormalities, and severe behavioral problems.

Any of various musculoskeletal disorders; such as, carpal tunnel syndrome or tendinitis; that are caused by cumulative damage to muscles, tendons, ligaments, nerves, or joints: "Cumulative trauma disorders are characterized primarily by pain, weakness, and loss of feeling of the hands, wrists, arms, or shoulders resulting from highly repetitive movements."

"The term cumulative trauma disorder is now also known as: repetitive strain injury, repetitive stress injury, repetitive stress syndrome, or repetitive motion injury."

A mood disorder characterized by numerous alternating short cycles of hypomanic and depressive periods with symptoms like those of manic and major depressive episodes, but of a lesser severity. Also called, cyclothymia.

An infiltrative disorder is a condition caused by the diffusion or accumulation in cells or tissues of substances not normally found in them; as in a disease that causes infection, inflammation, or the presence of a foreign substance.

A condition in which normal chemical processes in which a plant or an animal uses food, water, etc. in order to grow and to make energy are disrupted; usually, because of a missing enzyme: Joe had to see his doctor regarding his metabolic disorder before it developed into a more serious condition.

A condition that can be caused by deficiency, an excess of one or more ingredients, or by a toxin or poisonous element in the diet:

• An intake of food that is deficient in carbohydrates is usually deficient in proteins, too.
• An excess substances can cause obesity and dental caries which are the most common disorders in the U.S.
• Toxic effects are disorders that can arise from the presence of poisonous substances in the food which may be caused by industrial pesticides, fertilizers, pollutants, and other chemicals which can also contaminate food.

In medicine, a neurosis in which people are continuously bothered by persistent ideas that make them do repetitive, ritualized actions which they have no control over: An obsessive-compulsive disorder often begins in adolescence and continues to fluctuate or come and go over time.

People with obsessive-compulsive disorders often suffer from very strong feelings of having to do something that can't be controlled by themselves and so they also may have depressions and anxieties.

For a long time, obsessive-compulsive disorders have been treated with psychoanalysis or behavior therapy.

Abnormal smelling which includes a loss of the ability to smell or a change in the way odors are perceived.

As for changes in the perceptions of olfactory disorders, some people notice that familiar odors become distorted, or an odor that usually smells pleasant instead smells foul.

Olfactory disorders have many causes.

Most people who develop an olfactory disorder have recently experienced an illness or an injury.

Common triggers for olfactory disorders are colds and other upper respiratory infections and head injuries.

Among other causes of olfactory disorders are polyps in the nasal cavities, sinus infections, hormonal disturbances, or dental problems.

Exposure to certain chemicals; such as, insecticides and solvents, and some medications have also been associated with olfactory disorders.

People with head and neck cancers who receive radiation treatment are also among those who experience problems with olfactory disorders.

Olfactory disorders can have serious consequences; for example, the sense of smell often serves as a first warning signal, alerting us to the smoke of a fire or the odor of a natural gas leak and dangerous fumes.

Perhaps more important is that our chemosenses are sometimes a signal of serious health problems. Obesity, diabetes, hypertension, malnutrition, Parkinson's disease, Alzheimer's disease, multiple sclerosis, and alcoholic psychosis are all accompanied or are signaled by chemosensory problems resulting in olfactory disorders.