Collaborations Aging
The major goal of the work proposed is to utilize a novel method for quantitative sensory testing of tactile information processing to characterize an aging subject population. The method is driven by a conceptual model derived from neurophysiological observations of the dynamic changes that are evoked in SI cortex when stimuli that promote cortical regional interactions are presented to the skin. These sensory testing methods are atypical of the sensory testing methods that have dominated the literature for the past several decades primarily because they are designed from the perspective of generating measurable percepts that are most influenced by cortical-cortical interactions.
The metrics that we have developed thus far show sensitivity to systemic cerebral cortical alterations, and the primary target of the grant is to both collect data from a large number of subjects using the currently developed measures as well as develop additional diagnostic methods. A customized database has been implemented and will be used to enable observations across a number of variables in the subject population (medication history, etc.). The major target of the research is to establish baseline data to enable the launching of a more prospective longitudinal study for the diagnostic screening of the early detection of Alzheimer's Disease, and a major emphasis is on the overall development of the diagnostic device as a self contained unit that can be utilized by primary health care workers.
Traditional sensory perceptual metrics are influenced the most by skin sensitivity (detection thresholds ). The plot at the left demonstrate that with increasing age, people have higher thresholds and lower sensitivity.
Cortical Metrics that primarily reflect centrally mediated information processing – such as adaptation metrics - are not as impacted by age. In the figure below, the adaptation metrics demonstrate relative stability across a large age spectrum – as long as the subjects are healthy.
Impact of medications in the elderly: In a pilot study, we collected data from 20 adults, age range 65-78. 12 of those subjects were essentially medication-free and of those 12, 8 had results that were quite comparable to the data obtained for subjects under the age of 65. (One of the 4 subjects whose date was not comparable to controls was later diagnosed with a mild form of dementia, two of the 4 had fibromyalgia, and another had Parkinson’s). However, 6 subjects had been treated for high blood pressure for 3 or more months, and their data was significantly different from that of the control group. Note that in the graph below, a comparison of data obtained from the two populations between metrics is shown for both discrimination capacity and for adaptation. Although the impact on discriminative capacity in the medicated group is relatively insignificant, the impact of medications on the adaptation metric in this group appears quite significant. One goal of ongoing research is to determine the impact that commonly prescribed medications have on cortical information processing.
Comparison of medicated vs. non- medicated elderly subjects: Note that discrimination capacity is moderately, though not signficantly reduced in the medicated population. The adaptation metric for this population, however, is signficantly impacted. Lower discrimination values indicate that subjects are better at discrimination. Higher values for the adaptation task indicate that subjects adapted more - i.e., low values are markers of poor brain health. In general, the critical value is the difference between an individuals adaptation metric and their disrimination metric - the bigger the difference, the better.