Table 2.

Comparison of Variables Impacting Tissue Quality and Serving as Potential Limitations to Research Use in Brain Cancer vs Neurodegenerative Diseases

Variable impacting tissue quality	Neurodegenerative diseases	Brain cancer
Intracranial pressure	Decreasing brain mass due to brain atrophy and neuronal death	Increasing brain tumor mass leading to rise in intracranial pressure103
Hypoxia	Characterized in hypoxic/vascular dementia104 and poststroke Alzheimer’s disease105	Increasing levels of hypoxia with both functional and pathological implications106
Prolonged agonal state and subsequent lowered pH107	Dyspnea reported in both Dementia and amyotrophic lateral sclerosis.108	Reduced consciousness, respiratory distress, pneumonia and agonal breathing (death rattle) common during prolonged terminal phase108,110
	Bronchopneumonia most common cause of death in Alzheimer’s disease109
Necrosis	Necrotic and apoptotic pathways characterized in Alzheimer’s disease. Patchy foci of necrosis characterized111	Necrosis recognized as a hallmark feature of glioblastoma113
	Apoptosis primary mechanism of cell death in Parkinson’s disease.112
Hyperpyrexia114	Largely absent unless indicative of infection	Malignant fever or paraneoplastic fever associated with both primary115 and secondary brain cancers116