Differentiation of mild cognitive impairment using an entorhinal cortex-based test of virtual reality navigation.

The entorhinal cortex is one of the first regions to exhibit neurodegeneration in Alzheimer's disease, and as such identification of entorhinal cortex dysfunction may aid detection of the disease in its earliest stages. Extensive evidence demonstrates that the entorhinal cortex is critically implicated in navigation underpinned by the firing of spatially modulated neurons. This study tested the hypothesis that entorhinal-based navigation is impaired in pre-dementia Alzheimer's disease. Forty-five patients with mild cognitive impairment (26 with CSF Alzheimer's disease biomarker data: 12 biomarker-positive and 14 biomarker-negative) and 41 healthy control participants undertook an immersive virtual reality path integration test, as a measure of entorhinal-based navigation. Behavioural performance was correlated with MRI measures of entorhinal cortex volume, and the classification accuracy of the path integration task was compared with a battery of cognitive tests considered sensitive and specific for early Alzheimer's disease. Biomarker-positive patients exhibited larger errors in the navigation task than biomarker-negative patients, whose performance did not significantly differ from controls participants. Path-integration performance correlated with Alzheimer's disease molecular pathology, with levels of CSF amyloid-ß and total tau contributing independently to distance error. Path integration errors were negatively correlated with the volumes of the total entorhinal cortex and of its posteromedial subdivision. The path integration task demonstrated higher diagnostic sensitivity and specificity for differentiating biomarker positive versus negative patients (area under the curve = 0.90) than was achieved by the best of the cognitive tests (area under the curve = 0.57). This study demonstrates that an entorhinal cortex-based virtual reality navigation task can differentiate patients with mild cognitive impairment at low and high risk of developing dementia, with classification accuracy superior to reference cognitive tests considered to be highly sensitive to early Alzheimer's disease. This study provides evidence that navigation tasks may aid early diagnosis of Alzheimer's disease, and the basis of this in animal cellular and behavioural studies provides the opportunity to answer the unmet need for translatable outcome measures for comparing treatment effect across preclinical and clinical trial phases of future anti-Alzheimer's drugs.

The benefit of evolving multidisciplinary care in ALS: a diagnostic cohort survival comparison.

BACKGROUND: Care for people with amyotrophic lateral sclerosis (ALS) has altered at King's College Hospital over the last 20 years. The clinic has been a multidisciplinary, specialist, tertiary referral centre since 1995 with a large team with integrated palliative and respiratory care since 2006. We hypothesised that these changes would improve survival. METHODS: In this retrospective observational study, patients diagnosed with El Escorial definite, probable and possible ALS between 1995-1998 and 2008-2011 were followed up. The primary outcome measure was a chi-square test for the proportion of each cohort surviving. Kaplan-Meier survival analysis and Cox multivariate regression were secondary analyses. RESULTS: There was low reporting of some interventions. Five hundred and forty-seven people were included. Survival between the cohorts was significantly different (p = 0.022) with a higher proportion surviving during 2008-2011. Survival time was 21.6 (95% CI 19.2-24.0) months in the 2008-2011 cohort compared to 19.2 years (15.6-21.6) in the 1995-1998 cohort (log rank p = 0.018). Four hundred and ninety-three cases were included in the Cox regression. Diagnostic cohort was a significant predictor variable (HR 0.79 (0.64-0.97) p = 0.023). CONCLUSIONS: These results support the hypothesis that integrated specialist clinics with multidisciplinary input improve survival in ALS.