The syndrome of mild cognitive impairment (MCI) is heterogeneous in terms of etiology, symptoms, and prognosis. At post-mortem examination the majority of patients with MCI show various degrees of Alzheimer-type pathology whereas cerebrovascular changes and frontotemporal degeneration are rare. Follow-up studies have demonstrated that approximately 15 per cent of patients with MCI go on to develop dementia within one year. Taken together the available evidence suggests that in most instances MCI represents a pre-dementia stage of Alzheimer's disease, other neurodegenerative diseases, or cerebrovascular disease. Deficits in attention are a core feature of dementia and of MCI. In Alzheimer's disease impairment of attention is preceded by an initial amnestic stage. In subcortical cerebrovascular disease, frontotemporal degeneration, and Lewy Body disease, however, attentional deficits may occur earlier and be more prominent than impairments in memory and in other cognitive domains. Functional neuroimaging using fMRI and PET activation paradigms has been used to map attention and other cognitive domains on brain areas. In patients with MCI functional neuroimaging offers the opportunity to study progressive neurodegenerative and cerebrovascular diseases at a stage when patients still can perform complex and multiple tasks without being hindered by severe disturbance of thought and language. The diagnosis of these diseases at the stage of MCI has become possible by the use of imaging and CSF protein markers. From a clinical perspective one of the most interesting issues which may be addressed is brain plasticity. In MCI of various etiology one may expect compensatory utilization of brain areas which are not normally activated by a specific task. Longitudinal assessments of patients with MCI could help to determine the temporal course of functional cortical organization and to study associated behavioral changes. In this way, functional neuroimaging in MCI may contribute to a better understanding of the transition from MCI to dementia. Furthermore, functional neuroimaging may be useful to determine whether available treatments are effective in patients with MCI and how individual response can be predicted.
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Back to The IPA European Regional Meeting (1-4 April 2003) of IPA