Serum interleukin-6 levels correlate with the severity of dementia in down syndrome and in Alzheimer's disease

Introduction - Inflammatory processes are suspected in the pathomechanism of Alzheimer's dementia (AD) but the serum and cerebrospinal fluid (CSF) levels of inflammatory cytokines are not yet determined in the different forms of the disorder. Subjects and methods - Interleukin-6 (IL-6) levels were examined in the sera and CSF of patients with mild-moderate and severe stage of late onset sporadic type of AD and in the sera of demented Down syndrome (DS) probands with similar stages of AD and compared with data of age-matched healthy controls.Results - Normal serum IL-6 levels were found in the mild-moderate stage, but significantly increased levels were found in the severe stage of both dementia groups. The CSF concentrations remained within the normal range in all groups. Positive correlations between the serum IL-6 levels and age and the severity of the disease were present. Conclusion - These findings suggest a disease stage dependent general activation of the immune system both in sporadic AD and in DS with AD.