Self-Reported Cognitive Function in Persons with Nonneurological Chronic Diseases: A Systematic Review

Globally, one in three adults has a chronic condition. Many chronic diseases that are not neurological in nature (e.g., diabetes and heart failure) are increasingly associated with cognitive symptoms. However, the instruments used to assess cognitive symptoms in those with nonneurologic chronic illness are heterogeneous, and questions remain as to how cognitive symptoms may be related to demographic and clinical outcome variables, neurocognitive test performance, and other patient-reported outcomes. In this review, we describe associations among self-reported cognitive function, cognitive performance, and additional patient-reported outcomes as well as how cognitive symptoms are measured in nonneurologic chronic illness.

Multiple databases (PubMed, Medline, CINAHL, PsycInfo, EMBASE, SCOPUS, the Cochrane Library, and Academic Search Complete) were searched for studies from 1990 to 2020 that provided data on self-reported cognitive symptoms in those with nonneurological chronic conditions. Initial search yielded 304 articles, of which 32 met inclusion criteria. Quality assessment was conducted using the Critical Appraisal Skills Programme.

Thirty-two total studies were included: twenty cross-sectional, 10 longitudinal, and 2 randomized controlled trials. The tools used to assess self-reported cognitive function in the studies were heterogeneous: 28 unique tools were used. Thirty studies examined associations among self-reported cognitive function and other patient-reported outcomes. In 19 there were significant associations. Six studies showed no significant associations between neuropsychological tests and self-reported cognitive function; another 6 studies found a significant association.

Tools to assess cognitive symptoms were heterogeneous. In most studies, self-reported cognitive symptoms were not correlated with neuropsychological test results, but the majority of studies found a strong association between self-reported cognitive function and other patient-reported outcomes. Implications. Consensus on measuring cognitive symptoms would facilitate cross-study comparisons and facilitate scientific progress in those with nonneurological chronic conditions. Based on these results, there is a need to establish a standardized approach for self-reported cognitive function measurement in patients with nonneurologic chronic illness.