Revisiting MRI findings: circa 1990 (Bodon et al Mar J Bone Joint Surg)

They found 1/3rd of asymptomatic individuals to have a “substantial abnormality”.
Those under 60; 25% had a HNP, over 60 nearly 60% showed abnormalities; 40% HNP and 25% stenosis. Degeneration and bulging was found in more than a 1/3rd of those under 40 and in everyone 60 and older.
In 1994 similar findings were demonstrated in a study in the New England Journal of Medicine.
MRI T2 weighted images reveal that degeneration may begin in the teens especially in athletic individuals.
Degenerated discs are ubiquitous and assumed a source of pain but how they are “turned on” remains elusive…however an untenable or uncontrolled torque is usually the mechanical act that may initiates the pain (dietary and psychological factors notwithstanding).
I will guess that eventually MR scans (or another technology) will become so detailed as to reveal the microscopic fibers and the “active tear” where the pain probably generates. Why the pain fails to disappear after months in 10-15% is also elusive but recurrent mechanical stress and inefficient systemic healing must play a role.