Increased heat shock protein 70 gene expression in the brains of cocaine-related fatalities may be reflective of postdrug survival and intervention rather than excited delirium.

Cocaine-related fatalities can pose forensic challenges, particularly when accompanied by excited delirium (ED) syndrome and interventions by law enforcement and medical personnel. A recent report concluded that elevated heat shock protein 70 (HSP70) expression in autopsy brain samples constitutes a reliable forensic biomarker for the identification of ED as a cause of death. The present study quantified the abundance of both HSPA1A and HSPA1B gene (HSP70-encoding) transcripts in midbrain specimens from a series of cocaine-related fatalities and matched drug-free control subjects. HSP70 expression was increased significantly in cocaine abusers as a group compared to control subjects, irrespective of the presence or absence of ED. Furthermore, elevated HSP70 expression was predictive of a period of survival between cocaine use and death that included medical and/or police intervention. The present data do not support the assertion that HSP70 expression is a reliable brain biomarker for identifying ED as a cause of death.