Specific circumstances driving recurrence cannot be predicted, but predisposing factors stimulating recurrence have been investigated, including inflammation, aging, loss of MSC quality characterized by loss of FGF-2 production, lack of regenerative function, redirected adipogenic differentiation, estrogen deprivation, stromal injury, hypercoagulable states, angiogenic bursts, surgery-induced catecholamine production and inflammation, noradrenergic stress, and depression. The gene discussed is FGF2; the disease is major depressive disorder.