Anosognosia for memory disorder in people with acquired brain injury: a multidimensional investigation.

Anosognosia is a neuropsychological description of unawareness or denial of
impairment. Anosognosia for memory disorder (AMD) is a common, though poorly
understood, sequelae of acquired brain injury (ABI). Many theories have sought to
characterise the neurological, cognitive and motivational bases of anosognosia for
hemiplegia, though there are few theories specific to AMD. The studies have largely
failed to identify consistent neuroanatomical correlates or types of dysfunction. This
has led to the conclusion that anosognosia is a complex multidimensional clinical
phenomenon that requires subtle elaboration.
Part of the conceptual difficulty has been a function of the relative primitiveness of
models of awareness and the tendency for different indices of anosognosia to
measure different characteristics of the disorder in an unsystematic way. Recent
candidate models of anosognosia have distinguished between deficits in metacognitive
knowledge of memory disorder and deficits in online awareness (emergent and
anticipatory) of amnesia-related errors. We examined 14 patients with ABI and 15
healthy controls using a multidimensional approach that included a structured interview
to assess the metacognitive knowledge aspects of anosognosia and several
experimental measures to assess the different aspects of impaired online awareness.
Results indicated that different patients could be classified as anosognosic according
to which measure was used and that patients could be located on a spectrum of
anosognosia which varied along axes of partiality and specifity. The results suggest
that despite anosognosia, patients can improve their awareness across learning trials
though further research is required to substantiate this. It is hoped that studies such as
this, which strive for a developmental reciprocity between theory and service-based
practice, may contribute to a more pragmatic understanding of AMD in patients with
ABI.

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