Neuronal degeneration causes many neurological disorders that effect humans. Chronic neurodegeneration occurs in Alzheimer's disease (AD), ALS, Parkinson's disease, and Huntington's disease. Acute neurodegeneration results from trauma, hypoxia-ischemia (stroke and cardiac arrest), neurotoxins, radiation, and seizures. It has been theorized only recently that an abnormal activation of apoptosis in neurons may play a role in the disease process in humans with neurological injury. For postmitotic cells, apoptosis has irreplaceable consequences. However, much more work is necessary to accurately assess the contribution of apoptosis to the neurodegeneration in chronic and acute neuropathological disorders.