Falling is a frequent and major clinical problem among older adults, as well as in patients with chronic cerebrovascular diseases (CVD). At present, sequential (mixed) and simultaneously (dual-task) motor-cognitive trainings are the best approaches to affording patients more autonomy in their everyday motor independence while reducing fall risks and consequences. The objective of this study was to evaluate the efficacy of an advanced and innovative dual-task motor-cognitive rehabilitation program on fall risks in vulnerable older persons with chronic CVD. To this purpose, 26 consecutive older fallers with chronic CVD were recruited, and completed a mixed motor-cognitive or a dual-task motor-cognitive training program. Each patient also underwent two test evaluations to assess balance, gait, fear of falling, and walking performance at pre-and post-intervention. We found that our experimental motor-cognitive dual-task rehabilitation program could be an effective method to improve walking balance, gait, walking speed, and fear of falling, while reducing the risk of falls in older people with chronic CVD. Furthermore, results show that the simultaneous motor-cognitive training is more effective than the sequential motor-cognitive training. Therefore, our study brings innovative data, which can contribute positively to the management of this population.

Episodic memory impairment is the most common and initial cognitive symptom of AD related to the early involvement of the medial temporal lobe (MTL). In this study, we compared performance on tasks routinely used in the neuropsychological assessment of episodic memory to evaluate which test is more sensitive in predicting subsequent progression to AD in patients with amnestic mild cognitive impairment (a-MCI). For this purpose, we conducted a longitudinal study in 61 patients diagnosed as a-MCI at baseline and followed for 3 years. Baseline memory performance on the word list and short story tests was analyzed to determine the diagnostic ability of the tests to predict subsequent conversion to AD. Results showed that stable a-MCI patients performed worse on word list than on story recall, whereas patients who later converted to AD tended to have similar poor memory performance on both tasks. Furthermore, a pronounced memory decay passing from immediate to delayed recall on the short story test was significantly associated with both higher risk and faster mean time of conversion to AD. We hypothesized that this pattern of results is a consequence of the early involvement in converter a-MCI of MTL areas which are fundamental in the consolidation of new memory traces.

The aim of the current study was to test the accuracy of practice effects, that is, improvement in test performance due to repeated neuropsychological evaluations, in identifying patients with amnestic mild cognitive impairment (a-MCI) at greater risk of conversion to Alzheimer disease (AD). For this purpose, we conducted a longitudinal study of 54 patients diagnosed with a-MCI at the first assessment and followed-up for 4 years. During this time, 18 patients converted to AD. Baseline and 6- to 12-month follow-up performances on a large set of neuropsychological tests were analyzed to determine their diagnostic ability to predict later conversion to dementia. Results demonstrate that a lack of practice effects on episodic memory tests is an accurate prognostic indicator of late conversion to AD in a-MCI patients. In fact, even though the performance of both groups was substantially comparable at the baseline evaluation, stable a-MCI patients greatly improved their memory performance at retest after 6 to 12 months; instead, scores of converter a-MCI remained stable or decreased passing from baseline to follow-up. Standardized z-change scores on memory tasks, which were computed as a reliable measure of performance change, classified group membership with very good overall accuracy, which was higher than the classification of converter and stable a-MCIs provided by baseline or follow-up scores. We hypothesize that the lack of practice effects on memory tasks mirrors the early involvement of medial temporal lobe areas in converter a-MCI that are fundamental for the consolidation of new memory traces.

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Abstract. Retrograde amnesia (RA), which includes loss of memory for past personal events (autobiographical RA) and for acquired knowledge (semantic RA), has been largely documented in patients with amnestic mild cognitive impairment (aMCI). However, previous studies have produced controversial results particularly concerning the temporal extent of memory impairment. Here we investigated whether, with the onset of hippocampal pathology, age of memory acquisition and retrieval frequency play different roles in modulating the progressive loss of semantic and episodic contents of retrograde memory respectively. For this purpose, aMCI patients and healthy controls were tested for the ability to recall semantic and autobiographical information related to famous public events as a function of both age of acquisition and retrieval frequency. In aMCI patients, we found that the impairment in recollecting past personal incidents was modulated by the combined action of memory age and retrieval frequency, because older and more frequently retrieved episodes are less susceptible to loss than more recent and less frequently retrieved ones. On the other side, we found that the loss of semantic information depended only on memory age, because the remoteness of the trace allows for better preservation of the memory. Our results provide evidence that the loss of the two components of retrograde memory is regulated by different mechanisms. This supports the view that diverse neural mechanisms are involved in episodic and semantic memory trace storage and retrieval, as postulated by the Multiple Trace Theory.