Fractal Dimension Studies of the Brain Shape in Aging and Neurodegenerative Diseases

Abstract

The fractal dimension is a morphometric measure that has been used to investigate the changes of brain shape complexity in aging and neurodegenerative diseases. This chapter reviews fractal dimension studies in aging and neurodegenerative disorders in the literature. Research has shown that the fractal dimension of the left cerebral hemisphere increases until adolescence and then decreases with aging, while the fractal dimension of the right hemisphere continues to rise until adulthood. Studies in neurodegenerative diseases demonstrated a decline in the fractal dimension of the gray matter in Alzheimer's and multiple system atrophy of the cerebellar type, and in the fractal dimension of the white matter in amyotrophic lateral sclerosis, epilepsy, multiple sclerosis, multiple system atrophy of the cerebellar type, and stroke. Conversely, the fractal dimension of the gray matter increases in multiple sclerosis. Associations were found between the fractal dimension and clinical scores, showing the potential of the fractal dimension as a marker to monitor brain shape changes in normal or pathological processes and predict cognitive or motor function.