Atrophy is the degeneration or wasting away of a normally developed organ or tissue, resulting in a decrease in size or function. It can occur as a natural part of development or due to various factors such as mutations, nutritional problems, blood supply issues, hormonal imbalances, and nerve damage.

The underdevelopment of an organ or tissue during growth and development (known as developmental atrophy) is also considered a form of atrophy. Mutations that interfere with organ development, nutritional and blood supply issues, hormonal issues, and nerve damage to the affected organ are the causes of developmental atrophy. Similar factors can also cause atrophy in normal tissue.

The opposite of “atrophy” is “hypertrophy”. While atrophy refers to the shrinking or wasting away of an organ or tissue, hypertrophy refers to the increase in size or growth of an organ or tissue.

It is important not to confuse “atrophy” with “dystrophy”. Dystrophy involves the degeneration (decay) of tissue, usually due to a disease (often hereditary) or malnutrition. Examples of dystrophies include muscular dystrophy, Duchenne muscular dystrophy, and lipodystrophy.

Atrophy can occur as a natural part of development and aging. For example, the thymus gland shrinks during early childhood, and the tonsils undergo a process of involution during adolescence. Hair loss, skin wrinkles, muscle atrophy, and vaginal atrophy are other examples of atrophy that can occur with aging.

Examples of Atrophy

  • Muscle atrophy is the loss of mass and strength in an inactive muscle, usually caused by prolonged bed rest or cast immobilization. Due to the absence of gravity in space, astronauts also experience muscle atrophy; therefore, they must engage in regular exercise. Malnutrition can also cause muscle atrophy (cachexia).
  • Vaginal atrophy is associated with aging. It refers to the thinning, drying, and inflammation of the vaginal walls, often resulting from decreased estrogen levels during menopause.
  • Cerebral atrophy is the shrinkage of the cerebral hemispheres of the brain, which occurs in Alzheimer’s disease and many other neurological disorders.
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