A double-blind, placebo controlled study from the University College London found that a single large dose of CBD (600mg) does not alter the brain's reward-related regions. This is important because it was thought that CBD might provide this type of reward-network stimulation and help reduce the use of other drugs that do affect the brain's reward system, like THC.
But note, the study only examined a single dose, it did not study long-term, regular use. Most non-medical doses are MUCH smaller (1-10mg), so they should not affect the brain's reward systems either.
The full article about the research is from PsyPost here.