Seán McNally, who has PCA Alzheimer’s, is featured in TG4’s new documentary NéaltrúA moving new documentary on TG4 introduces viewers to the McNally family from west Belfast, united in facing dad Seán’s diagnosis of PCA (Posterior Cortical Atrophy) Alzheimer’s. Seán and Emer McNally at home in west Belfast“I take 13 pills every day just to keep right,” says Seán. In the vast majority of people, the cause of PCA is Alzheimer’s disease. Although PCA is usually caused by Alzheimer’s disease, the symptoms are very different. It is thought that this is caused by a build-up of abnormal proteins, which are also seen in Alzheimer’s disease.