Parkinson disease (PD) is characterized by destruction of dopaminergic neurons in the substantia nigra, but death of neurons in other brain areas in this disease is less well understood. A study in 15 rapidly autopsied PD brains has shown upregulated signalling via the proapoptotic protein Bid in the temporal cortex compared with that of age-matched controls. Such cortical pathology might have a role in PD-associated cognitive decline.