Acetylcholine Transmission Related to Age Evaluated by the Quantitative Electroencephalographic Vigilance-Index

Introduction: The objective for this study is to evaluate if there is an age-related decrease in the amount of available Acetylcholine for neurotransmission and to ensure that standard value for Vigilance-index is not age-dependent.

Methods:The average value for Vigilance-index, the ratio of Eyes open (E.O.) / Eyes closed (E.Cl.) average powers, based on four Electroencephalographic EEG epochs with eyes closed, and four epochs with eyes open calculated for a group of 30 healthy individuals aged between 17-67 years. The average Vigilance-index for this group compared with the average Vigilance-index for a baseline examination of 40 patients aged 66-93 years with memory complaints and examined for suspected dementia, with Vigilance-index below < 0.3, the normal value. Also, the correlation between age and Vigilance-index evaluated for the two groups and compared with the Pearson correlation coefficient and Spearman’s rank correlation coefficient.

Results:There was no apparent correlation between age and Vigilance-index when the diagram for 17-93 years of age (Figure 3) inspected visually. The Vigilance-index average value was similar for the younger group (0.14) and the elderly group (0.13). The correlation coefficients were inverse for the younger group, Pearson`s, -0.41 and Spearman`s rank correlation coefficient, -0.46 showing a decreasing Vigilance-index to age. A weak positive correlation to age for the elderly group, Pearson`s 0.16, and Spearman`s rank correlation coefficient 0.21, though within normal values range for Vigilance-index.

ConclusionThere were no substantial relation to age for Vigilance-index and no decisive age-related decrease in cholinergic transmission. Vigilance-index can, therefore reliable be used to determine pathological cholinergic status and identify dementia diseases with a cholinergic deficit, such as Alzheimer`s and Lewy body dementia irrespective of age. Other causes of dementia and diseases or conditions with dementia symptoms without cholinergic deficit also be separated irrespective of age.

Keywords: Electroencephalography; Desynchronization; Dementia; Acetylcholine; Cholinergic agents; Aged; Humans; Biomarkers; Reference Values; Synaptic Transmission