Journal of Alzheimer's disease : JAD
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Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation and aggregation of amyloid-β peptide and loss of forebrain cholinergic neurons, resulting in progressive loss of memory and irreversible impairment of higher cognitive functions. Several studies have accounted for the close relationship between AD and the central cholinergic system, suggesting that a dysfunction of acetylcholine containing neurons in the brain contributes significantly to the cognitive deficit of individuals with AD. ⋯ The implications for anesthesia are also discussed. This knowledge could be valuable to improve anesthesia performance and patient safety.
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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
Lost and found: bespoke memory testing for Alzheimer's disease and semantic dementia.
The neural network activated during Topographical Memory (TM) tasks in controls overlaps with the earliest affected regions in Alzheimer's disease (AD) but not with those of Semantic Dementia (SD). This suggests that clinical TM tests could be more bespoke to neural dysfunction in early AD and therefore more sensitive and specific. We hypothesized that TM impairment would be characteristic of AD but not of SD making it useful both for early diagnosis and differential diagnosis. ⋯ The VRLT achieved 95% sensitivity and 94% specificity in discriminating AD patients from controls; at the same cutoff, 70% of MCI patients were impaired. When combined with either naming performance or global dementia severity, there was complete separation of AD from SD. The VRLT is ecologically valid, highly sensitive to early AD, and useful in discriminating AD from the non-Alzheimer dementia, SD.
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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.