Background: Dementia is a neurodegenerative disease that requires the accompaniment of a caregiver who is in charge of assisting and supervising basic and psychosocial needs. Objectives: The objective of this article was to determine the influence of the caregiver on the cognitive and functional decline of patients with dementia. Methods: The method was a systematic review by searching the Scopus, Pubmed and Science Direct databases between the years 2010-2020. Findings and conclusion: In conclusion, the informal caregiver condition was the most reported by the investigations, generally assumed by wives and children; Caregiver characteristics such as personality, subjective interpretations of the functional status of adults with dementia, and caregivers' coping strategies were associated with a decrease in the rate of cognitive and functional impairment of people with dementia.