Patterns of Cognitive Decline and Rates of Conversion to Dementia in Patients with Degenerative and Vascular forms of MCI

Abstract

According to recent criteria, Mild Cognitive Impairment (MCI) represents a clinical condition with multiple cognitive presentations (amnesic and non amnesic) that can be supported by different types of brain lesions (mainly vascular and atrophic). In order to asses if the cognitive presentation and the rate of progression differ according to the type of brain pathology, two populations of MCI patients, characterized by hippocampal atrophy (n: 39) and vascular subcortical pathology (n: 36) respectively, on the basis of MRI findings, were investigated. Patients underwent an extensive neuropsychological test battery twice (at baseline and at two years follow-up), which is made up of the MMSE and various tests of episodic memory, short-term memory, visual-spatial abilities, executive functions, language, attention, praxis and psychomotor speed. Atrophic and vascular MCI patients showed a remarkably different pattern of impairment at the baseline. The former were significantly more impaired in episodic memory tasks. The latter were more impaired in an action naming task. At the follow up examination, the rate of progression to dementia was higher in atrophic (14/39) than in vascular (5/36) MCI patients. The comparison between neuropsychological scores obtained at the baseline and at the follow-up showed that atrophic MCI patients underwent a severe decline in several cognitive domains, whereas vascular MCI patients showed a significant decline only in those tasks requiring executive abilities. Our results confirm that a selective and severe defect of episodic memory is associated with hippocampal atrophy and that MCI patients with atrophic lesions are more likely to convert to Alzheimer's type dementia while MCI patients with vascular lesions are characterized by a slight decline in executive function over time and by a tendency to develop probable vascular forms of dementia.

Predictors of Future Cognitive Decline in Persons with Mild Cognitive Impairment

“…Thus, heterogeneous pathological processes may exist in MCI patients, who then experience different cognitive dysfunction patterns. Different cognitive profiles are also associated with different prognoses, with episodic memory impairment regarded as a predictor of development of AD [35,39,40], whilst working memory impairment is more strongly associated with the onset of other types of dementia, such as vascular dementia and Lewy body dementia [41,42,43,44,45]. …”

The Utility of Cerebral Blood Flow as a Biomarker of Preclinical Alzheimer’s Disease

“…Mild Cognitive impairment (MCI), or the presence of cognitive impairment in the absence of significant functional impairment, is arguably the most well-characterized risk factor for AD (Marra et al 2011). Across studies, MCI is associated with both increases and decreases in CBF, with increases in the MTL, anterior cingulate, insula, putamen, the left hippocampus, right amygdala, ventral striatum and the basal ganglia (Dai et al 2009; Alexopoulos et al 2012; Wolk and Detre 2012; Wierenga et al 2014), and decreases that reflect a lateral temporo-parietal-frontal pattern, extending to the MTL, posterior cingulate, and precuneus (Johnson et al 2005; Xu et al 2007; Dai et al 2009; Bangen et al 2012; Alexopoulos et al 2012; Wolk and Detre 2012; Wierenga et al 2014).…”

Drawing Disorders in Alzheimer’s Disease and Other Forms of Dementia

“…In this respect, it should be taken into account that cognitive characteristics of MCI individuals might correlate with performance on CDT. It is very important to acknowledge at this point that MCI patients are rather heterogeneous from the etiological point of view and that amnesic MCI can be considered as that most related to development of AD [95,96]. In line with this caveat is the fact that, a recent study contrasting MCI of the amnesic, dysexecutive, or multi-domain type on CDT [97] confirmed that aMCI did not differ from a matched sample of healthy controls, whereas both dysexecutive and multi-domain MCI individuals made a significantly larger number of errors in hand and number placement.…”