Neurodegeneration is classified as a massive death of neurons, and encompasses diseases such as Alzheimers, Parkinsons, and Huntingtons. Although many cells die due to necrosis, many cells in neurodegenerative disorders are killed via the apoptotic pathway. Excitotoxicity, which involves overstimulation of a cell via its glutamate receptors, is one of the major processes which can initiate cell death. Other inducers include mitochondrial dysfunction, oxidative stress, and abnormal protein aggregation. Surprisingly, both necrotic and apoptotic processes utilize a similar intracellular signaling cascade which uses caspase proteins to induce cell death. Abnormal protein accumulation causes Alzheimers, Parkinsons, and Huntingtons diseases.