Anosognosia or reduced awareness of cognitive and functional problems is a known clinical phenomenon in patients experiencing cognitive decline. It is common even in mild dementia syndromes and is often reported to increase with clinical disease progression (Aalten et al., Reference Aalten, van Valen, de Vugt, Lousberg, Jolles and Verhey2006). More recently it also has been described in older adults with cognitive-impairment-no-dementia (CIND) and mild cognitive impairment (MCI) (Greenop et al., Reference Greenop2011; Maki et al., Reference Maki, Amari, Yamaguchi, Nakaaki and Yamaguchi2012). The clinical significance of awareness is a topic of controversy in the literature and determining its biological correlates in brain function and structure is an ongoing challenge (Zamboni et al., Reference Zamboni2013; Ford et al., Reference Ford2014).

In this month's “Paper of the Month,” Lehrner and colleagues (Lehrner et al., Reference Lehrner2014) investigate the frequency of awareness, or the lack thereof, in a large cross-sectional sample of consecutive outpatients of a memory clinic in Vienna, Austria. Groups investigated were healthy older people as well as participants with subjective cognitive decline, amnestic or non-amnestic mild cognitive impairment (aMCI/naMCI), Alzheimer's disease, (AD) and Parkinson's disease (PD). Patients with PD were further grouped into cognitively healthy PD (PD-CH) and PD with naMCI or aMCI. The authors are interested in how over- or underestimation of awareness compares in the diagnostic groups and which variables are associated with this. The large clinical sample of 756 outpatients and 211 healthy controls investigated is a strength of the study, as is the thorough clinical assessment. Impairment of awareness was captured by measuring the difference between subjective memory complaints and objective performance on cognitive testing. The authors chose this method of comparison over the other common option of comparing subjective complaints with next of kin ratings. They preferred the chosen method as it avoids bias due to psychological factors which might affect the next of kin when rating the patient's level of awareness.

Several findings of this study are of interest and worth highlighting. The study design allows comparison of awareness, not only between patients and controls, but also between the various diagnostic groups. The reported result that levels of awareness significantly decrease from naMCI to aMCI and AD is what the clinician would expect, however the rather unusual inclusion of PD as a diagnostic group deserves additional attention. In the PD group awareness levels vary depending whether cognitive impairment is present or not. PD patients without cognitive impairment had very good awareness, however awareness levels diminish once aMCI or naMCI co-occurs with PD. Furthermore, correlates of awareness are investigated and whilst there is a strong and expected association with the memory domain and additional associations with attention and executive functions, additional non-cognitive factors are of interest here. Unawareness correlated with decreased levels of depression, functional impairment, higher age, and lower education. The paper further confirms that the concept of awareness is complex, with many influencing factors and with significant overlap between diagnostic groups. The authors conclude correctly that larger longitudinal studies would be of great value, since they could investigate how unawareness correlates with cognitive or functional decline over time and whether it has value as a negative prognostic indicator. Future studies should also include other relevant factors such as levels of anxiety, premorbid personality and type of relationship with next of kin. Further investigating awareness is important, as over- and underestimation of cognitive and functional abilities most likely has direct practical implications on quality of life for both patient and next of kin, quality of care and health economic outcomes in mild to severe cognitive impairment (Quinn et al., Reference Quinn, Clare, Jelley, Bruce and Woods2014).