Affiliations: [a] Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden | [b] Stress Research Institute, Stockholm University, Stockholm, Sweden | [c] Department of Psychology, University of Southern California, Los Angeles, CA, USA | [d] Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden | [e] Department of Medical and Surgery Sciences, University of Brescia, Brescia, Italy | [f] Stockholm Gerontology Research Center, Stockholm, Sweden
Correspondence:
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Correspondence to: Barbara Caracciolo, PhD, Aging Research Center, Gävlegatan 16, 113 30 Stockholm, Sweden. Tel.: +46 8 690 58 27; Fax: +46 8 690 68 89; E-mail: barbara.caracciolo@ki.se.
Abstract: We investigated the relation of subjective cognitive impairment (SCI) and cognitive impairment no dementia (CIND) to common chronic diseases of the elderly and multimorbidity, and assessed the contribution of genetic background and shared familial environment to these associations. Subjects were 11,379 dementia-free twin individuals aged ≥ 65 from the Swedish Twin Registry. SCI was defined as subjective complaint of cognitive change without objective cognitive impairment and CIND was defined according to current criteria. In unmatched, fully-adjusted regression models, mental, musculoskeletal, respiratory, and urological diseases were all significantly associated with increased odds ratios (ORs) of SCI and CIND. Circulatory and gastrointestinal diseases were related to SCI only, while endocrine diseases were associated with CIND. The adjusted ORs of multimorbidity were 2.1 [95% confidence intervals (95% CI): 1.8–2.3] for SCI and 1.5 for CIND (95% CI: 1.3–1.8). A dose-dependent relationship was observed between number of chronic diseases and ORs for SCI but not for CIND. In co-twin control analyses, the chronic diseases-SCI association was largely unchanged. On the other hand, the chronic diseases-CIND association was no longer statistically significant, except for cancer, where an increased OR was observed. In conclusion, chronic morbidity is associated with both SCI and CIND but disease profiles do not always overlap between the two cognitive syndromes. The association is stronger when diseases co-occur, especially for SCI. Genetic and early-life environmental factors may partially explain the association of CIND but not that of SCI with chronic diseases.
