Journal of Alzheimer's disease : JAD
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Increasing evidence indicates that patients develop post-operative cognitive decline (POCD) following surgery. POCD is characterized by transient short-term decline in cognitive ability evident in the early post-operative period. This initial decline might be associated with increased risk of a delayed cognitive decline associated with dementia 3 to 5 years post-surgery. ⋯ Inflammation and a maladaptive stress response might also contribute to the pathophysiology of this disorder. Future research needs to identify predisposing factors, and then strategies to protect against POCD and subsequent dementia. The field also needs to adopt a more rigorous approach to codifying the frequency and extent of early and delayed post-operative cognitive decline.
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The evaluation and management of patients with cognitive decline pose many diagnostic and therapeutic challenges. While most cognitive disorders need a standard screening for common reversible causes, the diagnosis of `not so usual' causes are delayed and often missed. ⋯ Many more metabolic, nutritional, endocrinal, toxic, post operative, autoimmune, cerebrovascular, genetic, infectious, and hemorheological factors are now emerging as unusual causes. This review deals with the recognition and evaluation of these unusual causes of cognitive decline.
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Comparative Study
The outcome of elderly patients with cognitive complaints but normal neuropsychological tests.
Elderly patients may present with prominent cognitive complaints and have performances in neuropsychological tests within the normal range for the age and education, and thus do not fulfill the criteria for mild cognitive impairment (MCI). There is insufficient evidence to support the clinical decision in these cases ("pre-MCI"). Forty-three subjects, 11 controls, 15 "pre-MCI," and 17 MCI, were followed for about three and half years with neuropsychological testing and magnetic resonance imaging including volumetric measurements of the hippocampus and amygdala. ⋯ In contrast, all control subjects remained stable and had no volumetric decreases. As expected, MCI patients underwent significant deterioration in several neuropsychological tests, often progressed to Alzheimer's disease, and showed decreases both in total hippocampal and amygdalar volumes. Elderly people presenting with cognitive complaints may be in an initial phase of a degenerative disorder and should be followed clinically, even if they have normal neuropsychological tests.
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Cognitive dysfunction in the elderly commonly observed following anesthesia has been attributed to age-related neuronal changes exacerbated by pharmacotoxic effects. However, the extent to which these changes may persist following recovery from surgery is still largely unknown. This study investigates the long-term effects of anesthesia on cognitive functioning after orthopedic surgery in 270 elderly patients over the age of 65 who completed a computerized cognitive battery before and 8 days, 4 and 13 months after surgery. ⋯ On the other hand, a clear dissociation effect was observed for several areas of visuospatial functioning which persisted up to the 13-month follow-up. This specific pattern of visuospatial deficit was found to be independent of apolipoprotein E genotype and closely resembles what has recently been termed vascular mild cognitive impairment, in turn associated with subtle sub-cortical vascular changes. The observation of only minor differences between persons operated by general and regional anesthesia makes it difficult to attribute these changes directly to the anesthetic agents themselves, suggesting that cognitive dysfunction may be attributable at least in part to peri-operative conditions, notably stress and glucocorticoid exposure.
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An inverted U-shape function between cortisol levels and memory performance has been reported in studies on both young animals and humans. Yet little is known about this relationship in normal aging or in older subjects with cognitive impairment. This issue is particularly significant since increased levels of cortisol have been reported in Alzheimer's disease (AD). ⋯ Higher cortisol levels were associated with better memory performance in healthy elderly (p=0.005), while higher cortisol levels were correlated with poorer memory performance in MCI subjects (p=0.011). No correlation between cortisol and memory was found in the AD group (p > 0.05). These results suggest that the relationship between cortisol levels and memory performance in the aging process could vary according to the presence or absence of cognitive impairment.