Figure 8. Overall contribution of age to BPH pathogenic mechanisms. BPH/LUTD is a disease that occurs through the normal course of aging and often manifests clinically as bladder outlet obstruction (BOO). The main contributing factors of BOO include proliferation, smooth muscle, and fibrosis. Treatments currently include anti-proliferation agents (5ARI) and anti-smooth muscle agents (α-blockers); anti-fibrosis agents remain to be examined.