Parkinsonian signs and substantia nigra neuron density in decendents elders without PD.
Ross GW, Petrovitch H, Abbott RD, Nelson J, Markesbery W, Davis D, Hardman J, Launer L, Masaki K, Tanner CM, White LR. Parkinsonian signs and substantia nigra neuron density in decendents elders without PD. Ann Neurol. 2004 Oct; 56(4):532-9.