On the involvement of the locus ceruleus in Parkinson's disease
Abstractof theSIR: In an earlier issue of this journal, Sudarsky et al.1 described postmortem findings in four Parkinsonâs disease patients who had advanced dementia. They noted that dementia in these cases was associated with a relative absence of the cytoskeletal abnormalities common to Alzheimerâs disease. They also discussed the possible involvement of the locus ceruleus (and other subcortical sites) in the dementia associated with Parkinsonâs disease. I feel that several points raised in that report need to be addressed. Considering that the peak age of onset for Parkinsonâs disease is during the sixth decade, these patients had a relatively early onset of symptoms (mean age at onset, 55 years). In addition, these cases very likely had long-term occupational exposure to metals or solvents (two plumbers, a printer, and a laborer were studied). Given the age of onset of the subjects and that exposure to certain substances, notably 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)2 and manganese,3 can result in parkinsonian symptoms, the cases Sudarsky et al. described may not truly represent idiopathic Parkinsonâs disease. All four cases displayed locus ceruleus neuropathology, as noted by the authors. Other reports have noted that the locus ceruleus is involved in the dementia associated with Parkinsonâs disease.