Mechanisms of cell death in neurodegenerative diseases: fashion, fiction, and facts.

Apoptosis has become a most popular concept of cell death. However, the term is now so widely used and employed in such general terms in relation to neurological diseases that its application is very problematic. In addition, with the exception of developmental conditions, there is essentially no evidence of apoptosis fulfilling the criteria of its classical definition in any of the important human neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, Amyotrophic Lateral Sclerosis, and Creutzfeldt-Jakob disease. Importantly, a number of new cell death forms have been described in the literature and there is good reason to pay attention to these emerging concepts as they may provide a rationale for the development of disease-specific therapies.