Selective impact of disease on short-term and long-term components of self-reported memory: a population-based HUNT study

Abstract

BackgroundSubjective memory is commonly considered to be a unidimensional measure. However, theories of performance-based memory suggest that subjective memory could be divided into more than one dimension.ObjectiveTo divide subjective memory into theoretically related components of memory and explore the relationship to disease.MethodsIn this study, various aspects of self-reported memory were studied with respect to demographics and diseases in the third wave of the HUNT epidemiological study in middle Norway. The study included all individuals 55 years of age or older, who responded to a nine-item questionnaire on subjective memory and questionnaires on health (n=18 633).ResultsA principle component analysis of the memory items resulted in two memory components; the criterion used was an eigenvalue above 1, which accounted for 54% of the total variance. The components were interpreted as long-term memory (LTM; the first component; 43% of the total variance) and short-term memory (STM; the second component; 11% of the total variance). Memory impairment was significantly related to all diseases (except Bechterew’s disease), most strongly to brain infarction, heart failure, diabetes, cancer, chronic obstructive pulmonary disease and whiplash. For most diseases, the STM component was more affected than the LTM component; however, in cancer, the opposite pattern was seen.ConclusionsSubjective memory impairment as measured in HUNT contained two components, which were differentially associated with diseases.

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“…Principle component analysis with varimax rotation was used to eliminate multicollinearity and extract predominant variables. Principle component (PC) with eigenvalue ≧ 1 was considered as statistically significant 26 . The first four principle components accounted for 79.24% of total variance.…”

Subjective working and declarative memory in dementia and normal aging

“…This study assessed subjective memory by classifying the MMQ items into two components, one related to long‐term declarative memory (episodic and semantic) and the other related to short‐term working memory …”

“…The MMQ consisted of nine items related to different aspects of memory and was originally intended to capture subjective memory in a single summed score. However, in this study, the nine SMIs in the MMQ were subdivided into two statistically independent groups comprising two components of memory (long‐term declarative memory and short‐term working memory) . Component I (declarative memory) included five SMIs covering retrieval of previously acquired information, that is events and knowledge (eg, “Do you have problems remembering the names of other people?”), and component II (working memory) included four SMIs covering retrieval of information regarding recent events, either from a short time ago or in ongoing activity (eg, “Do you have problems keeping track of a conversation?”).…”

“…The Meta‐Memory Questionnaire (MMQ); was used in the HUNT3 epidemiological health survey to study subjective memory in Norway . A recent study using the MMQ in normal elderly individuals showed that this instrument measures two statistically independent components of SMCs, one related to long‐term declarative memory and the other related to short‐term working memory . Interestingly, the working memory component of MMQ, but not the declarative component, was associated with having or having had a disease .…”

“…A recent study using the MMQ in normal elderly individuals showed that this instrument measures two statistically independent components of SMCs, one related to long‐term declarative memory and the other related to short‐term working memory . Interestingly, the working memory component of MMQ, but not the declarative component, was associated with having or having had a disease . These findings suggest that it could be useful to investigate the content and structure of SMC instruments, although this has not commonly been implemented.…”