Am I the right way up? Disturbances of spatial orientation in variants of Alzheimer’s disease
Day BL, Peters A, Ocal D, Gonzalez AS, Yong KX, Crutch SJ
1. Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology
2. Dementia Research Centre, UCL Queen Square Institute of Neurology
People with typical Alzheimer’s disease (tAD) tend to present with memory problems, but there are variants of the disease where this is not the case. Posterior cortical atrophy (PCA) is such a variant that initially can primarily affect parietal, occipital and occipitotemporal cortices leading to profound disturbances of higher-level visual processing. Additionally, anecdotal reports from people with PCA and their carers often describe problems that would seem to impinge on brain functions more concerned with spatial orientation, posture and balance. Some experiences can be transient and bizarre, such as perception of the environment being upside down for a brief period, perhaps suggesting a disturbance of visual-vestibular integration1,2. The disordered mechanisms underlying the various perceptual and motor disturbances that have been reported and their prevalence in PCA have hardly been investigated and so remain poorly understood. We have therefore undertaken an extensive series of studies investigating a range of perceptual and motor mechanisms in people with PCA (n=24), tAD (n=22), and healthy age-matched controls (n=21). The tests were designed to be suitable for most people in these cohorts and were aimed to tease out specific processes related to multi-sensory integration and spatial orientation. Our aims were to identify precise disturbances of known mechanisms and to build up a picture of how such deficits may coexist within an individual, how the pattern of deficits varies within and between cohorts, and ultimately to associate those patterns with neuroanatomical findings. Parts of these data will be presented.
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- Crutch SJ, Lehmann M, Schott JM, Rabinovici GD, Rossor MN, Fox NC (2012) Lancet Neurol 11, 170-178.