Suspected dementia: evaluation of 323 consecutive referrals

Clinical signs in functional cognitive disorders: A systematic review and diagnostic meta-analysis

OBJECTIVE

Functional cognitive disorder (FCD) accounts for around a third of patients attending specialized memory clinics. It is also overrepresented in patients with other functional and somatic diagnoses. So far, no long-term diagnostic validity studies were conducted, and a positive diagnostic profile is yet to be identified. We aimed to review the literature on diagnostic signs and symptoms that allow for a discrimination between FCD and neurodegeneration.

METHODS

Systematic review of Ovid-Medline®, Embase and PsycINFO databases. Relevant clinical features were extracted including demographics, symptom history, comorbidities, language and interaction profiles and cognitive assessments. Studies with quantifiable diagnostic accuracy data were included in a diagnostic meta-analysis.

RESULTS

Thirty studies (N = 8602) were included. FCD patients were younger, more educated, and more likely to have a family history of older onset dementia, abrupt symptom onset, and higher rates of anxiety, depression and sleep disturbance. Promising language profiles include longer duration of spoken answer, elaborated examples of memory failures, ability to answer compound and personal questions, and demonstration of working memory during interaction. The pooled analysis of clinical accuracy of different signs revealed that attending alone and bringing a handwritten list of problems particularly increase the odds of a FCD diagnosis. Current evidence from neuropsychometric studies in FCD is scarce.

CONCLUSIONS

Our systematic review reinforces that positive signs contribute for an early differentiation between FCD and neurodegeneration in patients presenting with memory complaints. It is the first to attain quantitative value to clinical observations. These results will inform future diagnostic decision tools and intervention testing.

Functional cognitive disorders: a systematic review

Cognitive symptoms are common, and yet many who seek help for cognitive symptoms neither have, nor go on to develop, dementia. A proportion of these people are likely to have functional cognitive disorders, a subtype of functional neurological disorders, in which cognitive symptoms are present, associated with distress or disability, but caused by functional alterations rather than degenerative brain disease or another structural lesion. In this Review, we have systematically examined the prevalence and clinical associations of functional cognitive disorders, and related phenotypes, within the wider cognitive disorder literature. Around a quarter of patients presenting to memory clinics received diagnoses that might indicate the presence of functional cognitive disorders, which were associated with affective symptoms, negative self-evaluation, negative illness perceptions, non-progressive symptom trajectories, and linguistic and behavioural differences during clinical interactions. Those with functional cognitive disorder phenotypes are at risk of iatrogenic harm because of misdiagnosis or inaccurate prediction of future decline. Further research is imperative to improve diagnosis and identify effective treatments for functional cognitive disorders, and better understanding these phenotypes will also improve the specificity of diagnoses of prodromal degenerative brain disease.

Correlation of Alzheimer disease neuropathologic changes with cognitive status: a review of the literature

Clinicopathologic correlation studies are critically important for the field of Alzheimer disease (AD) research. Studies on human subjects with autopsy confirmation entail numerous potential biases that affect both their general applicability and the validity of the correlations. Many sources of data variability can weaken the apparent correlation between cognitive status and AD neuropathologic changes. Indeed, most persons in advanced old age have significant non-AD brain lesions that may alter cognition independently of AD. Worldwide research efforts have evaluated thousands of human subjects to assess the causes of cognitive impairment in the elderly, and these studies have been interpreted in different ways. We review the literature focusing on the correlation of AD neuropathologic changes (i.e. β-amyloid plaques and neurofibrillary tangles) with cognitive impairment. We discuss the various patterns of brain changes that have been observed in elderly individuals to provide a perspective for understanding AD clinicopathologic correlation and conclude that evidence from many independent research centers strongly supports the existence of a specific disease, as defined by the presence of Aβ plaques and neurofibrillary tangles. Although Aβ plaques may play a key role in AD pathogenesis, the severity of cognitive impairment correlates best with the burden of neocortical neurofibrillary tangles.

Neuropathology and cognitive impairment in Alzheimer disease: a complex but coherent relationship

Amyloid plaques and neurofibrillary tangles (NFTs) are the pathological hallmarks of Alzheimer disease (AD). There is controversy regarding the use of current diagnostic criteria for AD and whether amyloid plaques and NFTs contribute to cognitive impairment. Because AD is specific to humans, rigorous and comprehensiveclinicopathologic studies are necessary to test and refine hypotheses of AD diagnosis and pathogenesis. Neither the clinical nor the pathological aspects of AD evolve in a linear manner, but thepredictable sequence of AD pathology allows for stage-based correlations with cognitive deterioration. We discuss subsets of patients with clinical dementia who lack amyloid plaques and NFTs and, conversely, whether individuals without antemortem cognitive impairment can harbor severe AD-type pathological findings at autopsy. There are many medical, technical, and anatomical challenges to clinicopathologic studies in AD. For example, at least two thirds of persons older than 80 years have non-AD brain diseases that can effect on cognitive function. We argue that existing data strongly support the hypothesis that both amyloid plaques and NFTs contribute to cognitive impairment.

Diagnostic yield of cerebral imaging in patients with acute confusion

OBJECTIVE

Acute confusion (AC) is a frequent reason for hospital admission in elderly patients. Although in majority of cases the cause is a systemic disorder (e.g., dehydration or septicaemia), patients are frequently subjected to cerebral imaging. This study was undertaken to find clinical predictors of normal cerebral computed tomography (CCT) or magnetic resonance imaging (MRI) scans in AC.

METHODS

Retrospective study of 294 patients admitted with AC of unknown origin, of whom 178 received cerebral imaging.

RESULTS

The rate of pathological imaging studies was 14%. The best single predictor of a normal brain scan was the absence of focal signs. Patients without focal abnormalities and either fever or dehydration had a probability of 0.96 of having a normal CCT or MRI. In demented patients without focal signs, the predictive value for a normal brain scan was 0.98, and if either patients with drowsiness were excluded or the existence of fever or dehydration was added as a selection criterion, all patients had normal scans.

CONCLUSIONS

Patients with AC without focal signs and with either evidence for a medical aetiology of delirium or prediagnosed dementia are at a very low risk of having focal lesions in their CCT or MRI.

Evaluation of various methods of assessing symptoms of cognitive impairment and dementia

BACKGROUND AND PURPOSE

The effect of different diagnostic criteria for detecting dementia in both epidemiological and stroke cohort studies has been shown, but comparison between different assessment methods has only seldom been done. We compared both assessment methods and diagnostic criteria for dementia in a large well-defined stroke cohort.

SUBJECT AND METHODS

A group of 227 of 486 patients aged 55 to 85 years who 3 months after ischemic stroke completed a comprehensive neuropsychological test battery, structured clinical mental status examination of defined cognitive domains with expanded Mini-Mental State Examination. The criteria for dementia were those of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III, DSM-III-R) and the National Institute of Neurological Disorders and Stroke-Associated Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN).

RESULTS

The main differences between clinical and neuropsychological examinations were seen in memory functions: clinically 24.7% and neuropsychologically 54.2% had impairment in short-term memory and 10.4% versus 5.3% in long-term memory. Accordingly, the prevalence of dementia varied greatly: It was clinically 14.1% by DSM-III, 9.7% by DSM-III-R and 8.4% by NINDS-AIREN criteria. The corresponding frequencies based on neuropsychological evaluation were 27.3%, 4.0% and 25.6%. Between these 3 diagnostic criteria the concordance varied in clinical testing between 59.4%-68.8% (kappa 0.72-0.79) and in neuropsychological testing between 14.5%-81.1% (kappa 0.20-0.86). The concordance between clinical and neuropsychological testing was 56.8% (kappa 0.42) by DSM-III, 31.6% (kappa 0.35) by DSM-III-R and 25.5% (kappa 0.24) by NINDS-AIREN.

CONCLUSIONS

The frequency of poststroke dementia and cognitive decline varied sharply when different systems of diagnostic classification and methods were used. This may have serious influences on investigation and treatment of patients. We underline the importance of further debate and studies to refine the categories of cognitive impairment used in the setting of CVD.

Clinical and radiological determinants of prestroke cognitive decline in a stroke cohort

OBJECTIVES

Stroke seems to be related to dementia more often than previously assumed and vascular factors are also related to Alzheimer's disease. The pathophysiology of poststroke dementia includes ischaemic changes in the brain, a combination of degenerative and vascular changes, and changes only related to Alzheimer's disease. Some cognitive decline recognised after a stroke may be due to pre-existing cognitive decline. The aim of this study was to determine the clinical and radiological determinants of prestroke cognitive decline.

METHODS

The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischaemic stroke completed a comprehensive neuropsychological test battery; structured medical, neurological, and mental status examination; interview of a knowledgeable informant containing structured questions on abnormality in the cognitive functions; assessment of social functions before the index stroke; and MRI.

RESULTS

Frequency of prestroke cognitive decline including that of dementia was 9.2% (31/337). The patients with prestroke cognitive decline were older, more often had less than 6 years of education, and had history of previous stroke. Vascular risk factors did not differ significantly between these two groups. White matter changes (p=0.004), cortical entorhinal, hippocampal, and medial temporal atrophy (p<0.001), cortical frontal atrophy (p=0.008); and any central atrophy (p<0.01), but not the frequencies or volumes of old, silent, or all infarcts on MRI differentiated those with and without prestroke cognitive decline. The correlates of prestroke cognitive decline in logistic regression analysis were medial temporal cortical atrophy (odds ratio (OR) 7.5, 95% confidence interval (95%CI) 3.2-18.2), history of previous ischaemic stroke (OR 4.4, 95% CI 1.8-10.6), and education (OR 0.9, 95% CI 0.8-0.9).

CONCLUSIONS

History of previous stroke, but not volumes or frequencies was found to correlate with prestroke cognitive decline. Other associating factors were rather those usually associated with degenerative dementia: white matter changes and cerebral atrophy; and in multiple models medial temporal cortical atrophy and education. The possible overlap between two or more underlying diseases must be remembered in diagnosis and treatment of patients with vascular cognitive impairment.

Progression and outcome of patients in a Canadian dementia clinic

Five hundred and fifty-three patients were referred to a Canadian dementia clinic for standardized evaluation. The majority (83.5%) had a dementia with Alzheimer's disease (AD) accounting for 89% of dementias. Patients with probable AD who were followed for five years had variable rates of progression, increased mortality (37.1%, 2.5 times the expected rate) and a high rate of institutionalization (79%). Simple demographic (age) and social factors (marital status) were strong predictors for institutionalization. It was extremely difficult at presentation to predict the rate of progression. The prevalence of AD in autopsied cases was 62.5%. Clinic patients were younger, had milder dementias, and were more likely to have AD than patients identified in the course of a contemporaneous population-based dementia prevalence study.

Reversible dementias

With so many conditions that can manifest in dementia, the question arises as to how extensive an evaluation need be done on the individual patient presenting with dementia. Thorough physical, neurologic, and psychiatric examinations are the cornerstones of the work-up, with special attention paid to the history, use of medications, and mental status of the patient. Laboratory tests recommended by the National Institutes of Health Consensus Conference on Differential Diagnosis of Dementing Diseases include a complete blood count, electrolyte and metabolic screen, thyroid panel, vitamin B12 and folate levels, syphilis serology, urinalysis, chest radiograph and electrocardiogram, and head CT scan. These evaluations are sufficient to diagnose the majority of treatable dementias. Other evaluations including magnetic resonance imaging, electroencephalography, cerebrospinal fluid examination, cerebral blood flow and metabolism measures (rate of cerebral blood flow, single photon emission computed tomography, and positron-emission tomography), and brain biopsy all can be of additional assistance in diagnosing the cause of the dementia when justified by the clinical setting. When the appropriate diagnosis is made, therapy is directed at the primary disorder. Successful treatment of the primary condition may result in stabilization or partial or complete reversal of the cognitive disturbance. In some instances, judicious pharmacologic management of the accompanying behavioral disturbance may be required.

Evaluation of 110 consecutive patients with dementias: a prospective study

We prospectively investigated 131 consecutive cases (both in- and outpatients) of suspected dementia to evaluate the relative frequency of different types of dementia in Chinese patients. Dementia was confirmed in 110 cases (84.0%). In contrast to the Western series, vascular dementia (39.1%) was slightly more frequent than the Alzheimer's disease (36.4%). Twelve cases (10.9%) of potentially treatable dementia were found. Careful clinical observation was the most useful part of the evaluation. CT scan of brain was the most useful laboratory test.

Cross-national comparisons of the occurrence of Alzheimer's and vascular dementias

The relative occurrence of Alzheimer's and vascular dementias is examined in various countries using data of four types: incidence, prevalence, clinic and neuropathological studies. There is clear evidence that Alzheimer's dementia is more common than vascular dementia in Great Britain and North America and, to a lesser extent, in Scandinavia. The evidence from other countries with predominantly Caucasian populations is more limited, but also supports a predominance of Alzheimer's dementia. By contrast, the evidence from Japan generally shows that vascular dementia is more common. The more limited evidence available from China also supports a preponderance of vascular dementia. There is a need for studies directly comparing the occurrence of Alzheimer's dementia in Caucasian and Oriental populations.

Accuracy of the clinical diagnosis of vascular dementia: a prospective clinical and post-mortem neuropathological study

Brains from a prospective study of demented patients were investigated post mortem. Of the 27 patients with clinical diagnosis of vascular dementia, 23 showed multiple cerebral infarcts but senile plaques and neurofibrillary tangles were absent or in insignificant numbers. This gives an accuracy of 85%, a figure higher than previously documented.