Patients with posterior cortical atrophy (PCA) face complex visual-processing disturbances. Professor Sebastian Crutch attempts to describe them. “One moment, someone with PCA could be seeing something; the next, it could vanish before their eyes. Some people with PCA describe it as looking at the world through a fractured mirror,” says the Professor of Neuropsychology at the Dementia Research Centre, University College London (UCL).

PCA is a rare degenerative neurological disease affecting the posterior cortex, causing a range of complex disturbances in visual processing. Precise estimates of how many people have this form of dementia are difficult to determine – largely because it’s still under-recognised and misdiagnosed, but some studies have suggested that around 5% of those diagnosed with early-onset Alzheimer’s disease (AD) may have PCA.