Preserved online response to feedback but impaired consolidation of information about performance in Alzheimer’s Disease

Loss of awareness of symptoms, cognitive impairments and the disease itself, also termed anosognosia, is a common feature of Alzheimer's disease (AD). We aimed to investigate the mnemonic and executive origins of anosognosia in AD, as proposed by the Cognitive Awareness Model. A reaction time task was used to assess awareness of task performance in people with AD (PwAD; n = 10), healthy older adults (n = 19), and young adults (n = 22). Self-ratings of task performance after ten, 100 and 500 trials served as measures of short-, medium- and long-term performance monitoring. Electrophysiological responses to positive and negative performance feedback were recorded. Three components related to feedback processing were analysed: the feedback-related negativity (FRN), the P300, and the Late Positive Component (LPC). Our results showed that PwAD and healthy older adults were less accurate in medium- and long-term performance monitoring, whereas short-term monitoring was intact. The FRN amplitude was sensitive to feedback valence, showing increased amplitudes following negative feedback in all groups. PwAD and healthy older adults had reduced P300 amplitudes, and PwAD also had reduced LPC amplitudes after negative feedback. This may indicate deficits in attention and memory processes related to performance monitoring. Our study suggests a critical role of mnemonic (i.e. impaired consolidation) rather than executive factors in loss of awareness in PwAD.