ABSTRACT
Physiological ß-amyloid autoantibodies (Aß-autoantibodies) are currently investigated as potential diagnostic and therapeutic tools for Alzheimer's disease (AD). In previous studies, their determination in serum and cerebrospinal fluid (CSF) using indirect ELISA has provided controversial results, which may be due to the presence of preformed Aß antigen-antibody immune complexes. Based on the epitope specificity of the Aß-autoantibodies, recently elucidated in our laboratory, we developed (a) a sandwich ELISA for the determination of circulating Aß-IgG immune complexes and (b) an indirect ELISA for the determination of free Aß-autoantibodies. This methodology was applied to the analysis of serum samples from healthy individuals within the age range of 18 to 89 years. Neuropsychological examination of the participants in this study indicated non-pathological, age-related cognitive decline, revealed especially by tests of visual memory and executive function, as well as speed-related tasks. The ELISA serum determinations showed significantly higher levels of Aß-IgG immune complexes compared to free Aß-autoantibodies, while no correlation with age or cognitive performance of the participants was found.
Subject(s)
Alzheimer Disease/diagnosis , Amyloid beta-Peptides/immunology , Antigen-Antibody Complex , Autoantibodies , Cognitive Dysfunction/diagnosis , Adult , Aged , Aged, 80 and over , Alzheimer Disease/blood , Amino Acid Sequence , Antigen-Antibody Complex/blood , Autoantibodies/blood , Cognitive Dysfunction/blood , Enzyme-Linked Immunosorbent Assay/methods , Epitopes/genetics , Female , Germany , Humans , Immunoglobulin G/immunology , Male , Middle Aged , Molecular Sequence Data , Neuropsychological TestsABSTRACT
A number of studies have demonstrated enhanced slow wave activity associated with pathological brain function e.g. in stroke patients, schizophrenia, depression, Morbus Alzheimer, and post-traumatic stress disorder. However, the association between slow wave activity and healthy aging has remained largely unexplored. This study examined whether the frequency at which focal generators of delta waves appear in the healthy cerebral cortex changes with age and whether this measure relates to cognitive performance. We investigated 53 healthy individuals aged 18 to 89 years and assessed MEG during a resting condition. Generators of focal magnetic slow waves were localized. Results showed a significant influence of age: dipole density decreases with increasing age. The relationship between cognitive performance and delta dipole density was not significant. The results suggest that in healthy aging slow waves decrease with aging and emphasize the importance of age-matched control groups for further studies. Increased appearance of slow waves as a marker for pathological stages can only be detected in relation to a control group of the same age.
