Reduced self-awareness across pathologies: Involvement of the Anterior Cingulate Cortex.

Awareness of illness is a form of self-knowledge. It concerns the ability to perceive, recognize, and evaluate a deficit in sensory, perceptual, motor, affective, or cognitive functioning and also to consider the impact of these disturbances on basic and instrumental daily-life activities (Antoine et al., 2004; Prigatano et al., 2005; Starkstein et al., 2006). Indeed, awareness of illness is a higher-order cognitive function concerning information about the pathological state, its functional consequence, and the way it affects the patient and his interaction with the environment. Considering the above, this phenomenon has raised much interest for its consequences on compliance with treatment, prognosis, and the patient’s quality of life. The neurocognitive approach highlights how impaired self-awareness is linked to brain pathology, particularly concerning focal lesions, motivational and emotional factors, and concomitant cognitive disturbances (McGlynn & Schacter, 1989). The anterior cingulate cortex, the insula, the parietal cortex, the medial and inferior gyri of the temporal lobe, the entorhinal cortex, the hippocampus and, more generally, the prefrontal cortex are thought to be involved in self-awareness functions (Johnson et al., 2002; Ochsner et al., 2005). In particular, the anterior cingulate cortex [ACC] has been implicated in: 1) emotion, motivation, and attention; 2) facial self-recognition, interoceptive and emotional awareness; 3) integration of conscious experience; 4) error detection, conflict-monitoring, and self-related information monitoring. Given the above, the ACC would play an important role in both core and introspective self-awareness (Philippi et al., 2012). The latter relies on higher-order executive, attentional and metacognitive functions which are found to be impaired in unawareness subjects. It is important to underline the role of the ACC as part of an attentional-monitoring system that is responsible for achieving the highest level of efficiency required by a specific task (Posner & Reichle, 1994). Indeed, monitoring dysfunctions are involved in reduced self-awareness in Alzheimer’s Disease (Amanzio et al., 2011, 2013), in Parkinson’s Disease (Amanzio et al., 2014), in acquired brain injury (Palermo et al., 2014), and bipolar disorders (Palermo et al., 2015). These findings suggest that distinct pathologies exhibit executive dysfunction in the context of overlapping circuits, where an important role is played by the ACC (Palermo et al., 2014, 2015). This chapter will discuss the role of the anterior cingulate cortex in the arising of awareness deficits in neurocognitive disorder, acquired brain injuries, mood disorders and psychosis. Significant neuropsychological and neuroanatomical data will be highlighted and similarities/differences across pathologies will be pointed out.