Incident cognitive impairment in young and middle-aged adults suffering from obesity: a systematic literature review

ObjectiveThis systematic review synthesizes longitudinal evidence on the association between obesity and cognitive impairment in adults aged 18 to 64. MethodsA comprehensive search of PubMed, PsycINFO, and Web of Science identified prospective studies comparing adults with obesity to those of normal weight, using validated cognitive tests.ResultsAmong a total of 4,871 studies, 4 met the inclusion criteria. Three studies evaluated global cognitive function in middle-aged adults. Two studies reported impairments in individuals with midlife obesity and a more rapid decline in those who were metabolically unhealthy. One study found no association. Long-term obesity was also linked to poorer global cognition in midlife. Executive functions appeared to be impacted by obesity. Research on memory was mixed, as two studies found a negative association with obesity, while two found no association. Methodological weaknesses included imprecise exposure measurements and inadequate adjustment for confounding factors.ConclusionsDespite evidence that obesity may increase the risk of cognitive impairment in midlife, evidence from a very limited number of studies is inconsistent, and an independent association remains unconfirmed. Future work should clarify which cognitive domains might be particularly vulnerable to obesity in younger adults, thereby guiding early and targeted interventions.PROSPERO registration: CRD42024573250Keywords: Adults, Cognitive functions, Cohort studies, Executive functions, Obesity