Series of reviews assesses clinically useful tools to identify, diagnose, and treat cognitive dysfunction

1. Series of reviews assesses clinically useful tools to identify, diagnose, and treat cognitive dysfunction from Alzheimer dementia

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M20-1500


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A series of systematic reviews provides evidence-based insights into several aspects of care related to Alzheimer disease and related dementias. The reviews examined cognitive tests for older adults with suspected cognitive impairment to distinguish Alzheimer dementia from mild cognitive impairment (MCI) or normal cognition, biomarker testing for neuropathologic Alzheimer disease for people living with dementia, and prescription drugs and supplement treatment for people living with clinical Alzheimer dementia. The three reviews are published in

Annals of Internal Medicine

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Researchers from the Geriatric Research Education & Clinical Center, Minneapolis VA Health Care System, and the AHRQ-funded Minnesota Evidence-based Practice Center reviewed 57 published articles to assess the benefits and harms of brief cognitive tests for identifying clinical Alzheimer-type dementia (CATD) in people with suspected cognitive impairment. They found that many brief individual cognitive tests (such as the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), and Brief Alzheimer Screen standalone tests; delayed list-recall memory tests; and semantic (category) fluency language tests) had high sensitivity and specificity for distinguishing CATD from normal cognition. However, brief cognitive tests were less accurate in distinguishing CATD from mild cognitive impairment. No studies reported on cognitive testing harms.

Researchers reviewed 24 published articles to assess the accuracy of biomarkers for distinguishing between neuropathologic Alzheimer disease (i.e., from autopsy) and other brain diseases in people with dementia, including 15 studies of brain imaging and nine of cerebrospinal fluid (CSF) tests. The researchers found that amyloid positron emission tomography (PET), fluorodeoxyglucose (FDG)–PET, and magnetic resonance imaging (MRI) were all highly sensitive for neuropathologic Alzheimer disease, and that single-photon emission computed tomography (SPECT) and several CSF tests were moderately accurate. Single studies suggested amyloid PET, FDG-PET, and CSF test combinations may add accuracy to clinical evaluation.

Finally, for prescription drugs and over-the-counter supplements, 55 studies were identified for cognitive and functional outcomes and 12 for neuropsychiatric outcomes. The researchers found that cholinesterase inhibitors showed slightly reduced short-term worsening of cognition and function of uncertain clinical significance. Benefits of memantine appeared less consistent and also of uncertain clinical significance. Also, insufficient evidence on benefits and harm was noted for prescription drugs on neuropsychiatric outcomes, and for supplements on cognitive, function, and neuropsychiatric outcomes.

According to the study authors, these reviews are important because they can help physicians and patients make informed decisions about diagnostic evaluation, treatment, and other important aspects of care.

Media contacts: For an embargoed PDF please contact Lauren Evans at

[email protected]

. To contact the lead author, Howard Fink, MD, MPH, please email him directly at

[email protected]

.

2. Eye movement may be the earliest warning sign of a potentially dangerous thiamine deficiency


Horizontal gaze-evoked nystagmus was common among patients with thiamine deficiency

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L19-0836


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Horizontal gaze-evoked nystagmus, a vision condition in which the eyes make repetitive, uncontrolled movements, may be one of the earliest warning signs of thiamine deficiency. This finding is important because early detection is necessary to avoid the risk for permanent neurologic deficits and early death. A case report is published in

Annals of Internal Medicine

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A researcher from the University of Illinois College of Medicine presented the case of a 29-year-old woman who was hospitalized for frequent vomiting over a 2 week period. While in the hospital, the patient reported unsteadiness when walking, vertigo, and objects seeming to move back and forth in her field of vision (oscillopsia). The clinician determined that she had intermittent nystagmus that was horizontal and left beat when she was looking straight ahead, and she could not keep her eyes in an eccentric, lateral position (bilateral gaze-holding failure). This type of nystagmus results from dysfunction of the neural integrator, which is located in the nucleus prepositus hypoglossi bilaterally in the floor of the fourth ventricle. The early manifestations of thiamine deficiency seem to cluster around susceptible brainstem nuclei located in the floor of the fourth ventricle, leading the clinician to suspect thiamine deficiency.

The patient improved with thiamine supplementation and the Wernicke triad of encephalopathy, ataxia, and ophthalmoplegia was avoided. According to the researcher, a careful ocular motor and vestibular examination may enable a diagnosis of thiamine deficiency before a patient develops dangerous manifestations of a thiamine deficiency.

Media contacts: For an embargoed PDF please contact Lauren Evans at

[email protected]

. The author, Jorge C. Kattah, MD, can be reached directly at 309-253-1793 (mobile) or

[email protected]

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3. Blood test for NT-proBNP levels unlikely to provide value in routine clinical evaluation of syncope

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M19-3515


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Testing serum concentrations of N-terminal proBNP (NT-proBNP) in patients reporting to the emergency department (ED) for syncope is unlikely to add value to the clinical evaluation. Findings from a prospective cohort study are published in

Annals of Internal Medicine

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The challenge of ED evaluation for syncope is to accurately identify the serious underlying conditions and patients at risk for short-term serious outcomes while reducing unnecessary investigations and hospitalization for the rest. Circulating concentrations of NT-proBNP is higher among patients with serious underlying conditions. Yet before natriuretic peptides, such as NT-proBNP, are incorporated into routine ED evaluation of syncope, it is important to determine their value.

Researchers from The Ottawa Hospital Research Institute studied 1452 adult patients with syncope at 6 EDs in 2 Canadian provinces to evaluate whether adding NT-proBNP testing to the Canadian Syncope Risk Score (CSRS) improves prediction of 30-day serious adverse events (SAEs). They found that found that NT-proBNP levels were substantially higher among patients with SAEs including those with arrhythmic or cardiac SAEs. However, compared with the prognostic information provided by the CSRS, the biomarker provided no additional benefit, regardless of the SAE subtype or whether the SAE was discovered after the initial ED visit. Given that the existing CSRS elements, including electrocardiogram results and troponin levels, are widely available and highly predictive of short-term SAEs, the researchers conclude that NT-proBNP measurement is unlikely to be useful in the routine ED work-up of syncope.

Media contacts:

For an embargoed PDF please contact Lauren Evans at

[email protected]

. To speak with the lead author, Venkatesh Thiruganasambandamoorthy, MBBS, MSc, please contact Amelia Buchanan at

[email protected]

or 613-297-8315.

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Also new in this issue:

One of My Demons: Crying (or a Lack of)
Alice S. Bellchambers, MBBS
Graphic Medicine

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G19-0054