Physical-psychological-cognitive multimorbidity: a narrative review

Physical-psychological-cognitive multimorbidity (PPC-MM) is a distinct phenotype in older adults, defined as the coexistence of chronic physical conditions, psychological disorders, and cognitive impairment. When all three domains are present, the adverse impact on patients may be greater than that associated with single diseases or physical multimorbidity alone. This review delineates operational definitions of PPC-MM across major cohort studies, summarizes global epidemiological characteristics, and synthesizes evidence on multi-level risk factors. Chinese older adults have a PPC-MM prevalence ranging from 5.8% to 17.2%, while European and American populations have a PPC-MM prevalence ranging from 1.2% to 4.3%. These differences may reflect variations in region, population, and diagnostic criteria. Specifically, the definition of physical conditions has been primarily centered on 7-10 disease categories, and psychological disorders are mainly defined by depressive symptoms, and cognitive impairment is assessed using cohort-specific short-form batteries. Low socioeconomic status, adverse childhood experiences, and circadian syndrome have been linked to PPC-MM. Possible mechanisms include hypothalamic-pituitary-adrenal (HPA) axis dysregulation, inflammaging-related immune crosstalk, and loneliness-related feedback loops. PPC-MM reflects interactions across social, psychological, behavioral, and biological factors. Management could move toward integrated care based on comprehensive geriatric assessment, which may help delay functional decline and improve quality of life.