Cognitive decline

About: Cognitive decline is a research topic. Over the lifetime, 29308 publications have been published within this topic receiving 1174689 citations.

Cerebral microinfarcts: the invisible lesions

Abstract: Summary The association between small but still visible lacunar infarcts and cognitive decline has been established by population-based radiological and pathological studies. Microscopic examination of brain sections shows even smaller but substantially more numerous microinfarcts, the focus of this Review. These lesions often result from small vessel pathologies such as arteriolosclerosis or cerebral amyloid angiopathy. They typically go undetected in clinical–radiological correlation studies that rely on conventional structural MRI, although the largest acute microinfarcts can be detected by diffusion-weighted imaging. In view of their high numbers and widespread distribution, microinfarcts could directly disrupt important cognitive networks and thus account for some of the neurological dysfunction associated with lesions visible on conventional MRI such as lacunar infarcts and white matter hyperintensities. Standardised neuropathological assessment criteria and the development of non-invasive means of detection during life would be major steps towards understanding the causes and consequences of otherwise macroscopically invisible microinfarcts.

Status of computerized cognitive testing in aging: A systematic review

Abstract: Background Early detection of cognitive decline in the elderly has become of heightened importance in parallel with the recent advances in therapeutics. Computerized assessment might be uniquely suited to early detection of changes in cognition in the elderly. We present here a systematic review of the status of computer-based cognitive testing, focusing on detection of cognitive decline in the aging population. Methods All studies purporting to assess or detect age-related changes in cognition or early dementia/mild cognitive impairment by means of computerized testing were included. Each test battery was rated on availability of normative data, level of evidence for test validity and reliability, comprehensiveness, and usability. All published studies relevant to a particular computerized test were read by a minimum of two reviewers, who completed rating forms containing the abovementioned criteria. Results Of the 18 test batteries identified from the initial search, 11 were appropriate to cognitive testing in the elderly and were subjected to systematic review. Of those 11, five were either developed specifically for application with the elderly or have been used extensively with that population. Even within the computerized testing genre, great variability existed in manner of administration, ranging from fully examiner-administered to fully self-administered. All tests had at least minimal reliability and validity data, commonly reported in peer-reviewed articles. However, level of rigor of validity testing varied widely. Conclusion All test batteries exhibited some of the strengths of computerized cognitive testing: standardization of administration and stimulus presentation, accurate measures of response latencies, automated comparison in real time with an individual's prior performance as well as with age-related norms, and efficiencies of staffing and cost. Some, such as the Mild Cognitive Impairment Screen, adapted complicated scoring algorithms to enhance the information gathered from already existing tests. Others, such as CogState, used unique interfaces and subtests. We found that although basic indices of psychometric properties were typically addressed, sufficient variability exists that currently available computerized test batteries must be judged on a case-by-case basis.

Accounting for bias due to selective attrition: The example of smoking and cognitive decline

Abstract: Background Selective attrition may introduce bias into analyses of the determinants of cognitive decline. This is a concern especially for risk factors, such as smoking, that strongly influence mortality and drop-out. Using inverse-probability-of-attrition weights (IPAWs), we examined the influence of selective attrition on the estimated association of current smoking (versus never smoking) with cognitive decline.

Cognitive deficits and associated neurological complications in individuals with Down's syndrome.

Abstract: Improvements in medical interventions for people with Down's syndrome have led to a substantial increase in their longevity. Diagnosis and treatment of neurological complications are important in maintaining optimal cognitive functioning. The cognitive phenotype in Down's syndrome is characterised by impairments in morphosyntax, verbal short-term memory, and explicit long-term memory. However, visuospatial short-term memory, associative learning, and implicit long-term memory functions are preserved. Seizures are associated with cognitive decline and seem to cause additional decline in cognitive functioning, particularly in people with Down's syndrome and comorbid disorders such as autism. Vision and hearing disorders as well as hypothyroidism can negatively impact cognitive functioning in people with Down's syndrome. Dementia that resembles Alzheimer's disease is common in adults with Down's syndrome. Early-onset dementia in adults with Down's syndrome does not seem to be associated with atherosclerotic complications.

Amyloid β oligomers constrict human capillaries in Alzheimer’s disease via signaling to pericytes

Abstract: Cerebral blood flow is reduced early in Alzheimer’s disease (AD). Because most of the vascular resistance within the brain is in capillaries, this could reflect dysfunction of contractile pericytes on capillary walls. Here we used live and rapidly-fixed biopsied human tissue to establish disease-relevance, and rodent experiments to define mechanism. We found that, in humans with cognitive decline, amyloid β (Aβ) constricts brain capillaries at pericyte locations. This was caused by Aβ generating reactive oxygen species, which evoked the release of endothelin-1 (ET) that activated pericyte ETA receptors. Capillary, but not arteriole, constriction also occurred in vivo in a mouse model of AD. Thus, inhibiting the capillary constriction caused by Aβ could potentially reduce energy lack and neurodegeneration in AD.