To be eligible for benefits, the worker must suffer from a full disability and be completely unable to perform any type of employment. However, being unable to perform work in a prior occupation is not sufficient grounds to qualify for SSDI benefits. Moreover, the disability must be due to a serious medical problem that doctors expect to be long-term — that is, to last at least a year or cause death. The medical condition causing the disability may be either mental or physical, but verified evidence showing a diagnosis by medical professionals must be presented in a claim.