The presence of the apolipoprotein E (APOE) Ε4 allele is a definite risk factor for the onset of Alzheimer’s disease (AD). Its presence seems to affect especially the memory in the early stage of the disease, but the effect on the progression of the disease and survival is still controversial. Some longitudinal studies could be influenced by variables other than APOE, such as the response to medical treatment, rehabilitation therapy and inclusion of patients at different stages of progression at baseline. Moreover, the inclusion in the same study sample of patients of different ages at onset of the disease (below 65 or above 80 years) appears arbitrary. In our study, we evaluated a population of newly diagnosed untreated AD patients at their first neuropsychological examination and with the onset of their first symptoms not longer than 3 years ago. In order to analyse the different effects of the APOE Ε4 allele on the different ages at the onset of the disease, we split the study sample into two groups: (1) subjects under 65 years [early-onset AD (EOAD); n = 30] and subjects over 70 years [late-onset AD (LOAD); n = 41], excluding subjects with an age of onset between 66 and 69 years. Our results show that the APOE Ε4 allele carriers are characterised by a different neuropsychological pattern at the disease onset; however, only in the EOAD group is this effect significant: in EOAD, the Ε4 allele carriers obtained worse performances in learning, long-term verbal memory and general intelligence tasks. On the contrary, in LOAD patients, the pattern of cognitive impairment at the onset is not dependent on the possession of an Ε4 allele in the genotype. Such data could suggest a careful control of the study sample concerning age at the onset of the disease since APOE could play a different role in EOAD and LOAD mainly due to the different pathogenic mechanism at the onset and evolution of AD.

We investigated whether MCI patients with hippocampal atrophy or multiple subcortical infarcts demonstrate neuropsychological patterns and markers considered typical of Alzheimer's disease (AD) and of vascular dementia (VD), respectively. An extensive neuropsychological battery, including tests of memory, visual-spatial and executive functions, language, attention, praxis and psychomotor speed, was administered to 36 mild cognitive impairment (MCI) patients with hippocampal atrophy and 41 MCI patients with multiple subcortical infarcts. Both groups of MCI patients were very mildly impaired and well matched in terms of MMSE scores. A clear, disproportionately severe, episodic memory disorder was observed in MCI patients with hippocampal atrophy. A less specific neuropsychological profile, consisting of impairment on an Action Naming task that is sensitive to frontal lobe lesions, was observed in MCI patients with multiple subcortical infarcts. In MCI patients, a disproportionately severe episodic memory impairment strongly points to an Alzheimer's type brain pathology, whereas the prevalence of executive deficits and other frontal lobe symptoms are a much weaker diagnostic marker of small vessel subcortical disease. (JINS, 2008, 14, 611-619.)

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.

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