Bernanke refers to studies by eg Barry Eichengreen (Golden Fetters, 1992), in which the gold standard is regarded as the main reason for the global slump, and he takes the view that, in those circumstances, abandoning the gold standard was a prerequisite for recovery from the Great Depression.
The gold standard helped spread the depression around the world, as it prevented countries with a balance of payments deficit from loosening their monetary policy even when their internal economic situation had required it.