The Effect of Different Diagnostic Criteria on the Prevalence and Incidence of Post-Stroke Dementia

The Value of Bayesian Methods for Accurate and Efficient Neuropsychological Assessment

OBJECTIVE

Clinical neuropsychology has been slow in adopting novelties in psychometrics, statistics, and technology. Researchers have indicated that the stationary nature of clinical neuropsychology endangers its evidence-based character. In addition to a technological crisis, there may be a statistical crisis affecting clinical neuropsychology. That is, the frequentist null hypothesis significance testing framework remains the dominant approach in clinical practice, despite a recent surge in critique on this framework. While the Bayesian framework has been put forward as a viable alternative in psychology in general, the possibilities it offers to clinical neuropsychology have not received much attention.

METHOD

In the current position paper, we discuss and reflect on the value of Bayesian methods for the advancement of evidence-based clinical neuropsychology.

RESULTS

We aim to familiarize clinical neuropsychologists and neuropsychological researchers to Bayesian methods of inference and provide a clear rationale for why these methods are valuable for clinical neuropsychology.

CONCLUSION

We argue that Bayesian methods allow for a more intuitive answer to our diagnostic questions and form a more solid foundation for sequential and adaptive diagnostic testing, representing uncertainty about patients' observed test scores and cognitive modeling of test results.

Cognitive Impairment in Patients with Stroke

Despite substantial advances in stroke care, vascular cognitive impairment remains a prominent source of disability. Unlike sensorimotor impairments, cognition often continues to decline after stroke. An aging population will increase the prevalence of vascular cognitive impairment, with stroke playing an important role. Ten percent of patients presenting with stroke have pre-stroke dementia; an additional 10% will develop incident dementia with a first stroke, and 30% with a recurrent stroke. While stroke increases the risk of cognitive impairment, the presence of cognitive impairment also impacts acute stroke treatment and increases risk of poor outcome by nearly twofold. There is substantial overlap in the clinical and pathological aspects of vascular and degenerative dementias in many patients. How they relate to one another is controversial. The treatment of vascular cognitive impairment remains supportive, focusing on treating vascular risk factors. Cognitive rehabilitation after stroke is an area of active research, and existing pharmacologic treatments have limited benefit. Heightened awareness of cognitive impairment in the setting of stroke is imperative for prognostication and management, impetus for research and, ultimately, the discovery of efficacious treatments.

Incidence and risk factors of vascular dementia in Thai stroke patients

BACKGROUND

Besides disability in stroke survivors, vascular cognitive impairment (VCI) can prevent these patients from living independently. The purpose of this study is to look for the incidence and risk factors of vascular dementia in Thai patients with stroke.

METHODS

Adults patients with ischemic stroke were prospectively included. Cognitive assessment was performed at 3-6 months after stroke onset. Montreal Cognitive Assessment (MOCA)- Thai version was used to evaluate cognitive function, with the cutoff point of 24/25 of MOCA to define cognitive impairment/normal cognition. Vascular mild cognitive impairment (VMCI) and vascular dementia (VAD) were diagnosed in those with cognitive impairment. Epidemiologic data, Apolipoprotein E (ApoE) status, and stroke characteristics were compared between patients with and without VAD.

RESULTS

There were 180 patients with the mean age of 65 years. Median time after stroke onset to have cognitive assessment was 6 months. Ninety patients (50%) had VMCI. VAD was diagnosed in 49 patients (27%). Mean Thai version of mental state examination (TMSE) and MOCA scores in patients with VAD were 20 and 12, respectively. Multivariate analysis showed that older age (OR 4.994, 95%CI 1.602-15.565, p-value = 0.006), lower education (OR 10.306, 95%CI 3.162-33.586, p-value < 0.001), history of stroke (OR 4.959, 95%CI 1.036-23.741, p-value = 0.045) and moderate to severe cerebral white matter lesions (OR 5.555, 95%CI 1.710-18.041, p-value = 0.004) were associated with VAD. ApoE 4 allele was found in 25% of the patients, but the presence did not show any association with the increased risk of VAD.

CONCLUSIONS

VAD occurred in 27% of the stroke patients. Older age, low education level, history of stroke, and the presence of moderate to severe white matter lesions were associated with the increased risk of VAD.

Decrease in post-stroke spasticity and shoulder pain prevalence over the last 15 years

OBJECTIVES

The usual complications after recent stroke such as disabling spasticity and shoulder pain seemed less frequent in recent years. This study examined the frequency of spasticity and shoulder pain in recent post-stroke patients over time in our physical and rehabilitation medicine department.

METHODS

This was a retrospective study of post-stroke inpatients over the last 15 years. Spasticity and shoulder pain prevalence were analyzed, as were demographic, clinical and stroke characteristics.

RESULTS

We reviewed medical records for 786 patients (506 men); mean age 58.1 years (SD 13.2); 530 (68%) with ischemic stroke and 256 (32.36%) hemorrhagic stroke. After a first increase from 2000 to 2006, the prevalence of disabling spasticity decreased from 2006 to 2015 (31%-10%; P<0.001). Shoulder pain at admission and during hospitalization also decreased (13% of patients in 2000 to 8% in 2015, P<0.001). Disabling spasticity was associated with shoulder pain (26% of patients with disabling spasticity presented shoulder pain at admission vs 7% with hyperreflexia of the deep tendon reflexes, P<0.05). Characteristics of stroke, time of admission after stroke and length of stay did not change over the years. We observed an increase in number of walking patients at admission and number with a functional paretic arm at admission and discharge (P<0.05), which may explain the increase in functional independence measure scores at admission and discharge (both P<0.05). Prevalence of cognitive disorders increased over the same period (24% in 2000 vs 63% in 2015, P<0.05).

CONCLUSIONS

Disabling spasticity and shoulder pain frequency in recent post-stroke patients decreased over the last 15 years, and functional abilities both at admission and discharge improved. Confirmation of these results in a multicentric study may be important evidence of an improvement in stroke healthcare both in stroke and physical and rehabilitation medicine units in the last 10 years in France and could affect future estimations of the need for rehabilitation care after stroke.

STROKOG (stroke and cognition consortium): An international consortium to examine the epidemiology, diagnosis, and treatment of neurocognitive disorders in relation to cerebrovascular disease

INTRODUCTION

The Stroke and Cognition consortium (STROKOG) aims to facilitate a better understanding of the determinants of vascular contributions to cognitive disorders and help improve the diagnosis and treatment of vascular cognitive disorders (VCD).

METHODS

Longitudinal studies with ≥75 participants who had suffered or were at risk of stroke or TIA and which evaluated cognitive function were invited to join STROKOG. The consortium will facilitate projects investigating rates and patterns of cognitive decline, risk factors for VCD, and biomarkers of vascular dementia.

RESULTS

Currently, STROKOG includes 25 (21 published) studies, with 12,092 participants from five continents. The duration of follow-up ranges from 3 months to 21 years.

DISCUSSION

Although data harmonization will be a key challenge, STROKOG is in a unique position to reuse and combine international cohort data and fully explore patient level characteristics and outcomes. STROKOG could potentially transform our understanding of VCD and have a worldwide impact on promoting better vascular cognitive outcomes.

Poststroke cognitive impairment and dementia: prevalence, diagnosis, and treatment

Three aspects of poststroke cognitive impairment and dementia are discussed in this review: prevalence; diagnosis; and treatment. The aim is to increase awareness of poststroke cognitive impairment in order to further stimulate strategies to recognize the condition and to prevent its progression. Approximately two-thirds of all middle-aged and elderly stroke patients develop cognitive impairment, and one in three develops dementia. The standard reference for diagnosis is a detailed neuropsychological examination. Short screening tests have been used for both clinical and research purposes, but their sensitivity is limited and there is no consensus as to which test is the most appropriate. The treatment of poststroke cognitive impairment and dementia is based on effective treatment of vascular risk factors, including lifestyle modification when needed.

Changes in cognitive function over 3 years after first-ever stroke and predictors of cognitive impairment and long-term cognitive stability: the Erlangen Stroke Project

BACKGROUND AND PURPOSE

Cognitive impairment (CI) is frequent after stroke, but data from population-based stroke cohorts on the natural course of CI are limited. The purpose of this study was to determine changes in cognitive status over 3 years after stroke.

METHODS

Data were collected from the Erlangen Stroke Project, an ongoing population-based stroke registry. The Mini-Mental State Examination (MMSE) for assessing global cognitive function was used; CI was defined as an MMSE score <24.

RESULTS

From February 1998 to January 2006, 630 patients with first-ever stroke were included. Prevalence rates of CI at 3 months, 1 and 3 years were 15, 13, and 12%. In multivariable analysis, stroke severity, i.e. Barthel index (p < 0.001), age (OR = 1.03; 95% CI = 1.00-1.05) and diabetes mellitus (OR = 2.03; 95% CI = 1.13-3.67) were associated with CI at 3 months. Recovery rate from CI at 3 months after stroke was found to be 31% over the following 3 years. Intact cognitive function rate was 71% over 3 years and inversely associated with age (OR = 0.96; 95% CI = 0.96-0.94) and stroke severity (p < 0.001).

CONCLUSION

CI is frequent among stroke survivors and associated with age, stroke severity, and diabetes mellitus, but recovery occurs in approximately one third of the patients over the course of 3 years. Factors affecting intact cognitive function over time are increasing age and stroke severity.

How predictive is the MMSE for cognitive performance after stroke?

Cognitive deficits are commonly observed in stroke patients. Neuropsychological testing is time-consuming and not easy to administer after hospital discharge. Standardised screening measures are desirable. The Mini-Mental State Examination (MMSE) is the test most widely applied to screen for cognitive deficits. Despite its broad use, its predictive characteristics after stroke have not been exhaustively investigated. The aim of this study was to determine whether the MMSE is able to adequately screen for cognitive impairment and dementia after stroke and whether or not the MMSE can predict further deterioration or recovery in cognitive function over time. To this end, we studied 194 first-ever stroke patients without pre-stroke cognitive deterioration who underwent MMSEs and neuropsychological test batteries at 1, 6, 12, and 24 months after stroke. The MMSE score 1 month after stroke predicted cognitive functioning at later follow-up visits. It could not predict deterioration or improvement in cognitive functioning over time. The cut-off score in the screening for 1 cognitive disturbed domain was 27/28 with a sensitivity of 0.72. The cut-off score in the screening for at least 4 impaired domains and dementia were 26/27 and 23/24 with a sensitivity of 0.82 and 0.96, respectively. The results indicated that the MMSE has modest qualities in screening for mild cognitive disturbances and is adequate in screening for moderate cognitive deficits or dementia in stroke patients 1 month after stroke. Poor performance on the MMSE is predictive for cognitive impairment in the long term. However, it cannot be used to predict further cognitive deterioration or improvement over time.

Cognitive function following stroke and vascular cognitive impairment

PURPOSE OF REVIEW

This review of the cognitive status following stroke and vascular cognitive impairment starts by questioning the concept of vascular dementia and related concepts. Our position is that in many cases these labels promote a superficial conceptualization of an inherently complex and heterogeneous phenomenon hampering a more detailed understanding.

RECENT FINDINGS

After stroke or disease of the cerebral vasculature, the cognitive and emotional outcome is dependent on a combination of three factors with the relative importance differing between causes. First, focal damage may lead to selective impairments that are dependent on the localization of the (grey matter) lesion. Second, diffuse neuronal dysfunction produces a more uniform profile of a decrease in mental speed, memory problems, and reduced executive functioning. Third, cognitive outcome is further modulated - notably in terms of severity - by patient variables such as age, sex, premorbid level of functioning, and comorbidity (e.g. hypertension).

SUMMARY

The complex character of the cognitive repercussions of stroke can be better harnessed by employing modern neuropsychological assessment procedures. This allows both a detailed categorization of the patients for the selection and effectiveness of therapeutic intervention, as well as the construction of reliable prognostic models.

Poststroke dementia

Dementia is one of the major causes of dependency after stroke. The prevalence of poststroke dementia (PSD)-defined as any dementia occurring after stroke-is likely to increase in the future. In community-based studies, the prevalence of PSD in stroke survivors is about 30% and the incidence of new onset dementia after stroke increases from 7% after 1 year 48% after 25 years. Having a stroke doubles the risk of dementia. Patient-related variables associated with an increased risk of PSD are increasing age, low education level, dependency before stroke, prestroke cognitive decline without dementia, diabetes mellitus, atrial fibrillation, myocardial infarction, epileptic seizures, sepsis, cardiac arrhythmias, congestive heart failure, silent cerebral infarcts, global and medial-temporal-lobe atrophy, and white-matter changes. Stroke-related variables associated with an increased risk of PSD are stroke severity, cause, location, and recurrence. PSD might be the result of vascular lesions, Alzheimer pathology, white-matter changes, or combinations of these. The cause of PSD differs among studies in relation to the mean age of patients, ethnicity, criteria used, and time after stroke. In developed countries, the proportion of patients with presumed Alzheimer's disease among those with PSD is between 19% and 61%. Patients with PSD have high mortality rates and are likely to be functionally impaired. These patients should be treated according to the current guidelines for stroke prevention.