In the literature it is commonly reported that several spatial abilities decline with normal aging, even though such a decline is not uniform. So far, it is not yet clear which spatial components present a normal age-related decline, which ones are preserved and at what point the deficit is so severe to represent an index of mild cognitive impairment (MCI) or a symptom of potential degenerative progression as in the early-stage Alzheimer's disease (AD). In particular, AD (from early onset) is characterised by impairments in constructive abilities, visuospatial intelligence, spatial short-term memory deficits, and disorders of spatial orientation (topographical disorientation). MCI indicates a condition, generally affecting older individuals, characterized by cognitive deficits including memory and/or non memory impairments and at high risk of progression to dementia. Three MCI subgroups have been distinguished and a very high risk of developing AD is associated to the amnestic MCI subtypes. Further, recent studies have suggested that the allocentric component of spatial memory might be taken as predictor of AD from MCI. Given the frequency of visuospatial deficits in early-stage AD, evaluation of visuospatial processes is a promising approach to find predictive markers of AD. Here we report a review of the literature exploring specific visuospatial components in normal aging, MCI, and AD. In this way we could shed some light on the role of these components in the progression from MCI to AD and pave the way for future studies.

AD and MCI subjects show unawareness for memory deficit and significant memory-monitoring disorder. This confirms that anosognosia is an important symptom of MCI. Similarities of patterns of impaired awareness between AD and MCI supports the view of a continuum of the anosognosia phenomenon in MCI and AD.

Although in recent years the relationship between cognition and gait in Parkinson's disease (PD) has received increasing attention, the specific connections between gait patterns and cognitive features are not fully understood. The objective of this study was to describe the gait patterns in patients affected by PD with or without mild cognitive impairment (MCI+ and MCI-, respectively). We also sought to find an association between gait patterns and specific cognitive profiles. Using a gait analysis system, we compared the gait patterns among MCI+ patients (n = 19), MCI- patients (n - 24), and age- and sex-matched healthy subjects (HS; n = 20) under the following conditions: (1) normal gait, (2) motor dual task, and (3) cognitive dual task. In PD patients, gait parameters were evaluated in both the off and on states. Memory, executive, and visuospatial domains were assessed using an extensive neuropsychological battery. Compared with MCI- PD and HS, MCI+ PD patients displayed reduced step length and swing time and impairment of measures of dynamic stability; these dysfunctions were only partially reversed by levodopa. We also found that dual-task conditions affected several walking parameters in MCI+ PD in the off and on states relative to MCI- PD and HS. Factor analysis revealed 2 independent factors, namely, pace and stability. The latter was strongly and directly correlated to the visuospatial domain. In conclusion, dysfunctions on specific gait parameters, which were poorly responsive to levodopa and highly sensitive to dual-task conditions, were associated with MCI in PD patients. Importantly, visuospatial impairment was strongly associated with the development of instability and more generally with the progression of PD.

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