Implicit awareness in anosognosia: clinical observations, experimental evidence, and theoretical implications

Effect of unawareness on rehabilitation outcome in a randomised controlled trial of multicomponent intervention for patients with mild Alzheimer's disease

Unawareness of deficit has been shown to affect the outcome of targeted cognitive intervention programmes applied to patients with Alzheimer' disease (AD), but the effects on multimodal therapeutic approaches have not yet been explored. This research investigated the efficacy of the Multi-Intervention Programme (MIP) approach on improving cognitive, functional, affective, and behavioural symptoms in people with mild AD. In addition, we examined whether the presence of unawareness influences the MIP outcomes. Sixty-one mild stage AD patients were randomly assigned to either an experimental group which carried out an MIP individually (48 sessions, 16 weeks duration), combining diverse cognitive tasks, training in daily life and recreational activities, or a waiting list group which did not receive any treatment for the same time period. The efficacy of MIP (vs. waiting list) was tested using various standardised neuropsychological, functional, and behavioural outcome measures. Planned analyses were carried out to determine the effect of unawareness versus awareness on such outcomes. The results showed that patients overall benefited from the MIP in terms of both cognitive and non-cognitive symptoms. AD patients with awareness of deficits showed positive effects on all outcome measures in comparison with the waiting list group, while AD patients with unawareness showed improvements in non-cognitive symptoms only. In conclusion, the presence of unawareness reduces the cognitive and functional effects of MIP in patients with mild AD.

Anosognosia for apraxia: experimental evidence for defective awareness of one's own bucco-facial gestures

Anosognosia is a multifaceted, neuro-psychiatric syndrome characterized by defective awareness of a variety of perceptuo-motor, cognitive or emotional deficits. The syndrome is also characterized by modularity, i.e., deficits of awareness in one domain (e.g., spatial perception) co-existing with spared functions in another domain (e.g., memory). Anosognosia has mainly been reported after right hemisphere lesions. It is however somewhat surprising that no studies have thus far specifically explored the possibility that lack of awareness involves apraxia, i.e., a deficit in the ability to perform gestures caused by an impaired higher-order motor control and not by low-level motor deficits, sensory loss, or failure to comprehend simple commands. We explored this issue by testing fifteen patients with vascular lesions who were assigned to one of three groups depending on their neuropsychological profile and brain lesion. The patients were asked to execute various actions involving the upper limb or bucco-facial body parts. In addition they were also asked to judge the accuracy of these actions, either performed by them or by other individuals. The judgment of the patients was compared to that of two external observers. Results show that our bucco-facial apraxic patients manifest a specific deficit in detecting their own gestural errors. Moreover they were less aware of their defective performance in bucco-facial as compared to limb actions. Our results hint at the existence of a new form of anosognosia specifically involving apraxic deficits.