After obtaining his medical degree at Université de Liège (Belgium) in 1972, Pierre Étienne moved to McGill University, where he did postgraduate work in neurochemistry in Theodore Sourkes’ laboratory.

From 1978 to 1983, Pierre Étienne directed a CIHR program grant on the biochemical, physiological and neuropathological basis of Alzheimer's disease that focused on the cholinergic hypothesis. He later did brain imaging studies at the Montreal Neurological Institute and clinical studies with serotonergic agents at the Allan Memorial Institute.

In 1989, he joined Pfizer as Director of Experimental Medicine where he was responsible for the entire early development program (phase 1 and phase 2A) for US- and Japan- discovered compounds, for exemple:

• Ziprasidone (Geodon)
• the SP antagonist program
• the CP 118991 (similar to Aricept)

In 2000 he became responsible for the full development and execution of all Pfizer clinical programs (phase 3) worldwide.

In 2003, he joined PhageTech, a biotechnology company committed to researching and developing new classes of synthetic antibiotics.The company became public in 2007 and was sold to The medecine Company in 2009.

In December 2009, Pierre Étienne joined the Douglas Institute as a physician specialized in geriatric psychiatry.