[A critical analysis of neuroimaging studies in relation to cognitive performance in multiple sclerosis patients]

Studying the cognitive impairment of multiple sclerosis (MS) patients is fundamental for a global understanding of this disease. Neuroimaging techniques might provide crucial data about the nature of this deficit and their progression. Accordingly to this idea, over the last years there has been a marked increase in the number of studies devoted to explore the possible relationship between the cognitive alterations of this clinical population and different sorts of neuropathological indexes provided by both, classical as well as by more recently developed techniques. The results of the studies using structural information provided by structural techniques, have revealed the important role of atrophic processes in the aethiology of cognitive decline in MS patients. However, this information needs to be complemented with newer indexes of neuropathological alterations in 'apparently normal' gray and white matter. On the other hand, functional magnetic resonance imaging studies have provided clear evidence of the existence and functional significance of neuroplastic processes that can mask the relationship between morphological markers of tissue damage and cognitive performance of MS patients. Those neuroplastic processes need to be taken into account as they might compensate the cognitive decline of this clinical population. In summary, the present review tries to provide a critic and integrative view of different studies assessing the relationship between cognitive impairment in MS patients and different kinds of information provided by neuroimaging techniques.