To be fair, I suspect the causal relationship here isn’t completely straight forward. First, mental health is one of the worst covered services under most health plans, so the folks pushing for more government funding for healthcare are going to earn some voters. Second, I think the overlap between the Democratic base and people with better access to therapy such as those in urban or suburban environments is likely to be statistically significant. If you’re depressed and live in New York, you’re likely to find more options available to you than if you live in the sticks in West Virginia.