Objective: There is limited understanding about how people in the severe stages of Alzheimer's disease (AD) experience and demonstrate awareness. We synthesised all available evidence with the aim of understanding how awareness is preserved or impaired in severe AD and what evidence there is for different levels of awareness according to the levels of awareness framework. Method: A systematic search of the following databases: Embase, PsycINFO, MEDLINE and Web of Science was carried out. A narrative synthesis and analysis was conducted of all included studies. All studies were assessed for quality using the AXIS and CASP tools. Results: Our findings suggest that lower level sensory awareness is relatively maintained in severe AD. Findings for higher level awareness are variable and this may be related to the diversity of methods that have been used to explore awareness in these circumstances. Conclusion: Awareness is complex, heterogeneous and varies significantly between individuals. Environmental and contextual factors have a significant impact on whether awareness is observed in people with severe AD. Adaptation of the environment has the potential to facilitate the expression of awareness while education of caregivers may increase understanding of people with severe AD and potentially improve the quality of care that is received.

Background Although diffusion tensor imaging (DTI) fractional anisotropy (FA) is commonly used to quantify neural injury, it is non-specific and affected by a number of microstructural changes. Objective To examine alterations in white matter (WM) associated with neonatal encephalopathy (NE), and relate these to tangible biophysical changes using the neurite orientation dispersion and density imaging (NODDI) model. Design/Methods We recruited with parental consent consecutive encephalopathic neonates (Thompson score ≥6) admitted to Calicut Medical College, India over a 6 month period. At age <3 wk diffusion tensor magnetic resonance imaging (DTI, TR/TE = 2800 ms/94 ms, 20 directions, b = 0&1000 s/mm2, 1.8 × 1.8 × 5 mm3) was performed at 1.5T (Siemens Avanto). Sarnat encephalopathy stage (none, mild, moderate or severe) was allocated at day 3. DTI data were fitted to the NODDI model, generating maps of orientation dispersion index (ODI) and neurite density index (NDI). These were compared between infants grouped by encephalopathy severity using tract-based spatial statistics (TBSS). Results Fifty-four infants were recruited; 31 had usable data. The mean FA skeleton is shown in green (Figure 1a). Compared to normal/mild (n = 22) the moderate/severe encephalopathy group (n = 9) had significantly reduced WM FA (Figure 1b: red p < 0.05; yellow p < 0.01) and increased radial diffusivity (RD, Figure 1c). This corresponded to a decrease in NDI (Figure 1d), but not ODI (Figure 1e). Conclusions In this cohort, NODDI fitting indicates that microstructural changes in NE may be due to a reduced neurite density. Further work will establish whether these findings are consistent with those obtained from gold-standard multi-shell diffusion data. Abstract 8.9 Figure 1