The prevalence of oligoclonal bands in the CSF of patients with primary neurodegenerative dementia

Background Recent guidelines from the United States and Europe on the diagnosis and management of dementia include advice that younger patients with dementia should undergo CSF examination, which frequently includes analysis for oligoclonal bands (OCB). The presence of CNS specific OCB has traditionally been considered suggestive of an inflammatory aetiology, although the interpretation of such a finding in the presence of a normal CSF white cell count and protein is more difficult. Methods We reviewed retrospectively the prevalence of OCB, determined using agarose isoelectric focusing, in a series of 131 well characterised patients with a final diagnosis of a degenerative dementia who had undergone CSF examination. Results The mean age of the patients was 60.0 (SD 8.4) years. Seventy (53%) patients had Alzheimer's disease (AD), forty seven (36%) had frontotemporal lobar degeneration (FTLD), seven (5%) had Dementia with Lewy bodies and the remaining seven (5%) patients had other rarer neurodegenerative dementias. Neuropathological examination had been performed in fifteen (11%) patients. CNS specific OCB were present in nine (7%) patients in this cohort, all of whom had normal CSF white cell counts: four AD patients (a prevalence of 6%), four FTLD patients (a prevalence of 9%), and one patient with Creutzfeldt-jakob disease (a prevalence of 25%). Investigation of these patients, including two with neuropathologically verified AD and one with post-mortem confirmed CJD, did not reveal an alternative aetiology for their dementia. Conclusion A central immune response can occur in primary neurodegenerative dementias, albeit uncommonly.