Metamemory: A construct with diagnostic utility in a cognitive disorders clinic?

Metamemory may be defined as introspective knowledge or self‐ awareness of one’s memory capabilities. The relationship between subjective memory judgments and objective memory performance may not be straightforward. Mismatch may lead to subjective memory complaints (SMC) in the absence of objective deficits. Nevertheless, since SMC may be associated with subsequent cognitive decline, cognitive screening might reasonably aim to address the metamemory construct. A pragmatic diagnostic test accuracy study was performed examining two simple tests which may be judged to access the construct of metamemory (i.e., subjective memory judgments): the Dementia Commissioning for Quality and Innovation (Dementia CQUIN) screening question (“Have you been more forgetful in the past 12 months to the extent that it has significantly affected your life? ”) and a five‐point SMC Likert scale (“In general, how would you rate your memory? ”: 1 = poor; 2 = fair; 3 = good; 4 = very good; 5 = excellent; ratings of either fair or poor defined as SMC+). Prior experience has been gained with administration of both these tests. A standard patient assessment cognitive screening instrument, the Mini‐Addenbrooke’s Cognitive Examination (MACE), was also administered, using the cut‐ off for cognitive impairment from the index study (MACE ≤25/30). Over 3 months (April‐June 2017), 50 consecutive new outpatients attending a dedicated cognitive disorders clinic were tested (F:M = 26:24, 52% female; age range 26‐84 years, median 60.5); 4 were diagnosed with dementia (DSM‐IV‐TR criteria; dementia prevalence = 0.08), 20 had MCI (Petersen criteria; MCI prevalence = 0.40); these two groups were combined as a “cognitive impairment” category (n = 24). The remainder (n = 26) were diagnosed with SMC. Standard measures of discrimination were calculated for individual tests (CQUIN, SMC Likert, andMACE). Results (Table 1) showed that SMC Likert and MACE were highly sensitive for cognitive impairment (>0.95), but all tests had low specificity (≤0.5). For the metamemory tests, the correct classification accuracy, positive, and negative predictive values were all around 0.5 (with the exception of negative predictive value of 0.80 for SMC Likert), whereas MACE achieved better scores for all these parameters. Since the standard patient assessment cognitive screening instrument, MACE, outperformed both the metamemory tests on all the measures of discrimination examined, this may cast doubt on the diagnostic utility of the metamemory construct. However, the study has a number of shortcomings. Patient numbers were small. As the study setting, a dedicated memory disorders clinic, was anticipated to have a high prevalence of cognitive impairment, it was surprising that so many patients answered “No” to the Dementia CQUIN screening question. Indeed, this study observed a lower self‐rating of memory impairment using the yes/no screening question (60%) than using the Likert scale (90%), the reverse of the findings in epilepsy clinic‐based patient cohorts. Similar studies with larger patient cohorts and in low prevalence settings (e.g., primary care and population‐based studies) are also required to evaluate further the screening utility of the metamemory construct.