Imagine you have a magic invisibility cloak that you wear everywhere you go. Even though people can’t see you, you can still influence their behavior, emotions, and thoughts. Well, it turns out that something similar may be happening in the brains of people with Alzheimer’s disease and mild cognitive impairment. A recent task-based functional magnetic resonance imaging (fMRI) study explored the existence of an implicit component of self-awareness in these individuals. While they may not show explicit awareness of their cognitive difficulties, there might be an unconscious part of their brain that regulates their responses. Although this concept has been studied behaviorally, this study was the first to investigate its neural basis using fMRI. The researchers found that patients with preserved explicit awareness exhibited a unique pattern of activation in the posterior cingulate cortex (PCC) when processing dementia-related words. On the other hand, patients who were unaware of their cognitive impairments showed a different pattern of PCC activation. Interestingly, the extent of PCC activation correlated with the level of implicit awareness. In other words, the more negatively activated the PCC, the lower the person’s implicit awareness was. These findings provide insights into how implicit self-awareness operates in Alzheimer’s disease and mild cognitive impairment. If you’re intrigued by this fascinating research, dive deeper into the details by exploring the underlying study!

BackgroundRecent models of anosognosia in dementia have suggested the existence of an implicit component of self-awareness about one’s cognitive impairment that may remain preserved and continue to regulate behavioral, affective, and cognitive responses even in people who do not show an explicit awareness of their difficulties. Behavioral studies have used different strategies to demonstrate implicit awareness in patients with anosognosia, but no neuroimaging studies have yet investigated its neural bases.MethodsPatients with amnestic mild cognitive impairment and dementia due to Alzheimer’s disease underwent functional magnetic resonance imaging (fMRI) during the execution of a color-naming task in which they were presented with neutral, negative, and dementia-related words (Dementia-Related Emotional Stroop).ResultsTwenty-one patients were recruited: 12 were classified as aware and 9 as unaware according to anosognosia scales (based on clinical judgment and patient-caregiver discrepancy). Behavioral results showed that aware patients took the longest time to process dementia-related words, although differences between word types were not significant, limiting interpretation of behavioral results. Imaging results showed that patients with preserved explicit awareness had a small positive differential activation of the posterior cingulate cortex (PCC) for the dementia-related words condition compared to the negative words, suggesting attribution of emotional valence to both conditions. PCC differential activation was instead negative in unaware patients, i.e., lower for dementia-related words relative to negative-words. In addition, the more negative the differential activation, the lower was the Stroop effect measuring implicit awareness.ConclusionPosterior cingulate cortex preserved response to dementia-related stimuli may be a marker of preserved implicit self-awareness.

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