Disorders of attentional processes

The term “attention” refers to a heterogeneous set of cognitive processes which allow an organism to successfully cope with a continuously changing external and internal environment, while maintaining its goals. Several of these processes rely on the functioning of fronto-parietal brain networks, often with a right-hemisphere predominance. Disorders of attention often occur in neurodegenerative conditions, where they can appear in the context of complex cognitive impairment profiles, or even constitute the central core of the syndrome, such as in posterior cortical atrophy. Here, we particularly focus on attention disorders such as the inability to process several visual objects at a time (simultagnosia), the unawareness of an object when presented in competition to another one (extinction), or when occurring on one side of space (visual neglect). Other disorders may affect the general ability to respond to external stimuli and to sustain attention over time, or to plan and coordinate different activities and inhibit inappropriate responses. These disorders are described with reference to the corresponding altered brain networks and to the most common diagnostic tests in clinical practice. We also describe in some detail four clinical cases of patients affected by posterior cortical atrophy, with different cognitive and anatomical profiles.