Variability in estimating the self-awareness of memory deficits

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The March International Psychogeriatrics Article of the Month is entitled ‘Awareness of memory deficits in subjective cognitive decline, mild cognitive impairment, Alzheimer’s disease and Parkinson’s disease’ by Johann Lehrner, Sandra Kogler, Claus Lamm, Doris Moser, Stefanie Klug, Gisela Pusswald, Peter Dal-Bianco, Walter Pirker and Eduard Auff

As the world population ages, we face sharp rises in prevalence rates for neurodegenerative diseases. In order to minimize entailing individual and societal burdens, early diagnosis is becoming increasingly important. Efforts to enable early recognition of impending cognitive decline led to the development of the concept of Mild Cognitive Impairment (MCI), which describes a transitional stage between normal age-related memory decline and dementia. Yet, not all individuals diagnosed with MCI can be considered as being in a prodromal phase of dementia. Accordingly, ongoing research is now focusing on the identification of (a) those individuals with MCI who are most likely to convert to dementia and (b) asymptomatic individuals in a pre-MCI stage. Yet, which early markers are available for their identification?

With some evidence pointing towards a connection between low memory awareness – an inability to (fully) recognize memory deficits – and subsequent memory decline, awareness measures bear potential as an important marker of underlying dementia pathologies. However, as research in this field is defined by inconsistencies, this hypothesis needs further investigation.

We therefore used data concerning our patients’ subjective memory appraisals and objective memory performance to create an awareness index, which allowed us to compare levels of awareness (and frequencies of memory overestimation) across healthy elderly people and patients with varying degrees of memory impairment. Our question was whether our approach would reveal characteristic awareness differences similar to prior research.

As expected, our findings suggest that self-awareness of memory deficits decreases as cognitive deficits – especially memory deficits – increase. Accordingly, the highest rate of overestimation of memory function was found among patients suffering from Alzheimer’s disease (63%), followed by amnestic MCI patients without and with Parkinson’s disease (46%, 38%), while patients with cognitive deficits other than memory (non-amnestic MCI) showed a tendency towards underestimation of memory function. Our analyses further revealed considerable between-group overlaps in awareness scores and strong influences of non-cognitive factors such as depression.

The main implication of our study is that memory awareness reflects objective deterioration to some extent, but that there is considerable inter-individual variability in awareness. It is this variability which gives rise to the question whether differences in awareness are predictive of future conversion to dementia.

We hold the view that research in this field is important insofar as awareness measures are of high practical relevance: As opposed to biomarkers and neuroimaging technologies, which are of restricted availability in primary care settings, both measures of subjective memory complaint and objective memory performance provide easily, time- and cost efficiently accessible sources of information. Moreover, they count among the standard repertoire of diagnosis in MCI and other dementia-related diseases. Researchers could use these data to further explore the diagnostic and predictive validity of awareness measures. We hope that our work inspires further research concerning memory awareness and strongly welcome any comments and remarks.

The full paper “Awareness of memory deficits in subjective cognitive decline, mild cognitive impairment, Alzheimer’s disease and Parkinson’s disease” is available free of charge for a limited time here.

The commentary on the paper, “Awareness of memory deficits in subjective cognitive decline, mild cognitive impairment, Alzheimer’s disease and Parkinson’s disease” is also available free of charge here.

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