Cognitive state following mild stroke: A matter of hippocampal mean diffusivity.

The hippocampus is known to play a vital role in learning and memory and was demonstrated as an early imaging marker for Alzheimer's disease (AD). However, its role as a predictor for mild cognitive impairment and dementia following stroke is unclear. The main purpose of this study was to examine the associations between hippocampal volume, mean diffusivity (MD) and connectivity and cognitive state following stroke. Eighty three consecutive first ever mild to moderate stroke or transient ischemic attack (TIA) survivors from our ongoing prospective TABASCO (Tel Aviv Brain Acute Stroke Cohort) study underwent magnetic resonance imaging scans within 7 days of stroke onset. Hippocampal volume was measured from T1 weighted images, hippocampal mean diffusivity was calculated from diffusion tensor imaging and connectivity was calculated from resting state fMRI. Global cognitive assessments were evaluated during hospitalization and 6 and 12 months later using a computerized neuropsychological battery. Multiple linear regression analysis was used to test which of the hippocampi measurements best predict cognitive state. All three imaging parameters were significantly correlated to each other (|r's| >0.3, P's < 0.005), and with cognitive state 6 and 12 months after the event. Multiple regression analyses demonstrated the predictive role of hippocampal mean diffusivity (ß = -0.382, P = 0.026) on cognitive state, above and beyond that of volume and connectivity of this structure. To our knowledge, the combination of hippocampal volume, mean diffusivity and connectivity in first ever post stroke or TIA patients has not yet been considered in relation to cognitive state. The results demonstrate the predictive role of hippocampal mean diffusivity, suggesting that these changes may precede and contribute to volumetric and connectivity changes in the hippocampi, potentially serving as a marker for early identification of patients at risk of developing cognitive impairment or dementia.

Gait measures as predictors of poststroke cognitive function: evidence from the TABASCO study.

BACKGROUND AND PURPOSE: Patients with stroke are at risk for developing cognitive impairment. We tested whether the assessment of balance and gait can enhance the prediction of long-term cognitive outcome in stroke survivors. METHODS: Participants were patients with first-ever, mild-moderate ischemic stroke or transient ischemic attack from the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study, a large prospective cohort study, who underwent 3-T MRI and were followed for ≥2 years using neurological, neuropsychological, and mobility examinations 6, 12, and 24 months after the index event. RESULTS: Data were available for 298 patients (age: 66.7±9.6 years). Forty-six participants (15.4%) developed cognitive decline (CD) over the 2 years of follow-up. The CD group and cognitively intact group did not differ in their neurological deficits or in their infarct volume or location. Nonetheless, 6 months after stroke, the Timed Up and Go test took longer in those who later developed CD (P<0.001). Additionally, the CD group also had lower Berg Balance Scale scores (P<0.001), slower gait (P<0.001), and fewer correct answers during dual-task walking (P=0.006). Separate analyses of the patients with transient ischemic attack revealed similar results. Multivariate regression analysis showed that Timed Up and Go times >12 s at 6 months after stroke/transient ischemic attack was a significant independent risk marker of CD 24 months after stroke (odds ratio=6.07, 95% confidence interval: 1.36-27.15). CONCLUSIONS: These results suggest that measures of balance and gait are significant risk markers of cognitive status 2 years after stroke. Relatively simple, performance-based tests of mobility may enhance the identification of stroke/transient ischemic attack survivors who have an increased risk of developing CD. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01926691.

Depressive symptoms following stroke and transient ischemic attack: is it time for a more intensive treatment approach? results from the TABASCO cohort study.

OBJECTIVE: To examine whether depressive symptoms after a stroke or a transient ischemic attack (TIA) increase the risk of cognitive impairment and functional deterioration at 2-year follow-up. METHODS: Participants were survivors of first-ever, mild-to-moderate ischemic stroke or TIA from the TABASCO prospective cohort study who underwent 3T magnetic resonance imaging and were examined by a multiprofessional team 6, 12, and 24 months after the event using direct interviews, depression scales, and neurologic, neuropsychological, and functional evaluations. The main outcome was the development of cognitive impairment, either mild cognitive impairment (MCI) or dementia. MCI was diagnosed by a decline on at least 1 cognitive domain (≥ 1.5 SD) of the Montreal Cognitive Assessment score and/or on the computerized neuropsychological battery, as compared with age- and education-matched published norms. Dementia was diagnosed by a consensus forum that included senior neurologists specializing in memory disorders and a neuropsychologist. RESULTS: Data were obtained from 306 consecutive eligible patients (mean age: 67.1 ± 10.0 years) who were admitted to the department of emergency medicine at the Tel Aviv Medical Center from April 1, 2008, to December 1, 2011, within 72 hours from onset of symptoms of TIA or stroke. Of these patients, 51 (16.7%) developed cognitive impairment during a 2-year follow-up. Multivariate regression analysis showed that a Geriatric Depression Scale (GDS) score ≥ 6 at admission and at 6 months after the event was a significant independent marker of cognitive impairment 2 years after the stroke/TIA (OR = 3.62, 95% CI, 1.01-13.00; OR = 3.68, 95% CI, 1.03-13.21, respectively). A higher GDS score at 6 months was also related to a worse functional outcome (P < .001). CONCLUSIONS: Our results support depression screening among stroke and TIA survivors as a tool to identify patients who are prone to have a worse cognitive and functional outcome. These patients may benefit from closer medical surveillance and a more intensive treatment approach. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01926691.

Cognitive state following stroke: the predominant role of preexisting white matter lesions.

BACKGROUND AND PURPOSE: Stroke is a major cause of cognitive impairment and dementia in adults, however the role of the ischemic lesions themselves, on top of other risk factors known in the elderly, remains controversial. This study used structural equation modeling to determine the respective impact of the new ischemic lesions' volume, preexisting white matter lesions and white matter integrity on post stroke cognitive state. METHODS: Consecutive first ever mild to moderate stroke or transient ischemic attack patients recruited into the ongoing prospective TABASCO study underwent magnetic resonance imaging scans within seven days of stroke onset and were cognitively assessed one year after the event using a computerized neuropsychological battery. The volumes of both ischemic lesions and preexisting white matter lesions and the integrity of the normal appearing white matter tissue were measured and their contribution to cognitive state was assessed using structural equation modeling path analysis taking into account demographic parameters. Two models were hypothesized, differing by the role of ischemic lesions' volume. RESULTS: Structural equation modeling analysis of 142 patients confirmed the predominant role of white matter lesion volume (standardized path coefficient ß =  -0.231) and normal appearing white matter integrity (ß =  -0.176) on the global cognitive score, while ischemic lesions' volume showed no such effect (ß = 0.038). The model excluding the ischemic lesion presented better fit to the data (comparative fit index 0.9 versus 0.092). CONCLUSIONS: Mild to moderate stroke patients with preexisting white matter lesions are more vulnerable to cognitive impairment regardless of their new ischemic lesions. Thus, these patients can serve as a target group for studies on cognitive rehabilitation and neuro-protective therapies which may, in turn, slow their cognitive deterioration.

Predictors for poststroke outcomes: the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study protocol.

BACKGROUND: Recent studies have demonstrated that even survivors of mild stroke experience residual damage, which persists and in fact increases in subsequent years. About 45% of stroke victims remain with different levels of disability. Identifying factors associated with poststroke cognitive and neurological decline could potentially yield more effective therapeutic opportunities. AIMS AND HYPOTHESIS: We hypothesize that data based on biochemical, neuroimaging, genetic and psychological measures can, in aggregate, serve as better predictors for subsequent disability, cognitive and neurological deterioration, and suggest possible interventions. DESIGN: The Tel-Aviv Brain Acute Stroke Cohort (TABASCO) study is an ongoing, prospective cohort study that will recruit approximately 1125 consecutive first-ever mild-moderate stroke patients. It is designed to evaluate the association between predefined demographic, psychological, inflammatory, biochemical, neuroimaging and genetic markers, measured during the acute phase, and long-term outcome: subsequent cognitive deterioration, vascular events (including recurrent strokes), falls, affect changes, functional everyday difficulties and mortality. DISCUSSION: This study is an attempt to comprehensively investigate the long-term outcome of mild-moderate strokes. Its prospective design will provide quantitative data on stroke recurrence, the incidence of other vascular events and the evaluation of cognitive, affective and functional decline. Identifying the factors associated with poststroke cognitive and functional decline could potentially yield more effective therapeutic approaches.