Aging, Loss Of Complexity Or Loss Of Adaptability
Jacob Sosnoff, Assistant Professor, Kinesiology, UIUC
It is well known that with advanced age there are decrements in physiological function. Lipsitz & Goldberger (1992) propose that this decrement in function results from a systemic loss of complexity. Recently, it has been suggested that aging is not characterized by a loss of complexity per se, but rather older adults are less able to adapt their output to environmental demands. The purpose of this current investigation is to further examine if aging is characterized by a loss of complexity or a loss of adaptability. In order to address this issue, young and old adults produced isometric force output to 6 visually presented targets of distinct fractal dimensions (constant (dimension = 0), sinusoidal (dimension = 1), black, brown, pink and white noise). The frequency content of the fractal waveforms was varied from 0-4 Hz, 0-8 Hz and 0-12 Hz in independent conditions. Older adults were found to have lower complexity in their force output as indexed by approximate entropy and spectral slope in the higher dimensional tasks, but less complexity in the lower dimensional tasks. Additionally, increases in frequency content in the white and pink noise waveforms lead to increases in the complexity of the young adults output, but had minimal effects on the older adult’s performance. Overall, this investigation provides evidence that there is not a loss of complexity with old age, but rather a loss of adaptability. Furthermore, it demonstrates that older adults’ decrement in motor function is in part a result of decreased ability to utilize available visual information.