Predictors of the psychosocial impact of being a carer of people living with Parkinson's disease: A systematic review

• Patient non-motor symptoms and quality of life and carer depression consistently predicted psychosocial outcomes.
• Carer involvement and protective factors (e.g. social support, personality) demonstrated promising findings.
• Demographics and disease factors were consistently found not to be predictors.
• Confident conclusions could not be drawn regarding the most important predictors.
• Future research should build upon psychological theory to improve understanding.

IntroductionCaring for a person with Parkinson's disease (PwP) can have a variety of negative consequences that may challenge their ability to continue their caring role. It is still unknown why some individuals adapt better than others in response to such burdens. This review is the first to synthesize and evaluate the evidence on the predictive factors of psychosocial outcomes in PwP carers.MethodsStudies which identified predictors of psychosocial outcomes for unpaid carers were included. PsychINFO, EMBASE, AMED, BNI and CINAHL databases were searched, supplemented by scanning of references lists of included studies and relevant journals from 2008 onwards. Quality was assessed using the NICE methodology checklist for prognostic studies.ResultsTwenty-nine studies were included in the review, providing a low-level of evidence. Carer burden was investigated in 18 studies and mental health and quality of life (QoL) in seven studies each. PwP non-motor symptoms and QoL and carer depression were consistently identified as predictors for at least one psychosocial outcome. Demographics and disease factors were consistently found not to be predictors. Carer involvement and protective factors (e.g. social support, personality) demonstrated promising findings but studies were too few or factors measured inconsistently.ConclusionConfident conclusions could not be drawn regarding the most important predictors that should be targeted in psychosocial interventions due to methodological weaknesses and lack of theoretical testing across the current literature. Future research should build upon psychological theory to gain a better understanding of the mechanisms that explain how carers adapt to caregiving.