Action naming in dementia

Recent studies of action naming in dementia report contradictory results. Some studies have shown that naming of pictured actions is impaired and indeed worse than naming of pictured objects, whereas other studies report the opposite result, i.e. action naming is better preserved than object naming. One reason for these conflicting results may be that actions vary in their relationships with object knowledge. Instrumental actions, e.g. hammering, require access to knowledge about a specific object (a tool), whereas non-instrumental actions can be named correctly without access to knowledge about a specific object, e.g. running. Moreover, many instrumental action names share a name relationship with the instrument used to perform the action (homophony), whereas other action names do not, e.g. digging. In this case report, we describe an anomic patient RS with dementia affecting his access to knowledge about objects from visual, verbal and tactile input. By contrast, RS displays relatively well-preserved knowledge and naming of actions. We found an effect of instrumentality on pictured action naming, i.e. actions that depict an actor using a tool are named less accurately than actions that depict an actor performing an action without a tool. We argue that the instrumentality effect is independent of the name relationship between the action and the object and also the visual complexity of the action. We consider several explanations of the instrumentality effect and conclude that an impairment to the areas underpinning sensory feature and sensorimotor information (specific to manipulation) can account for an effect of instrumentality on action naming in dementia.