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Definition

One type of aggravation for disability purposes is defined in the United States Code (USC) in this manner: "A preexisting injury or disease will be considered to have been aggravated by active military, naval, or air service, where there is an increase in disability during such service, unless there is a specific finding that the increase in disability is due to the natural progress of the disease." (38 USC 1153). This kind of aggravation, known as aggravation of a preexisting condition, is present when there is permanent increase in the severity of a condition during or as a result of military service and the increase is not due to the condition's natural progression.

Another type of aggravation is present when there is permanent increase in the severity of a nonservice-connected condition due to an already service-connected condition, and the increase is not due to the condition's natural progression. This is known as aggravation of a nonservice-connected condition by a service-connected condition, or secondary (Allen) aggravation.

Presumption of soundness will be discussed next.