Systematic Review And Meta-analysis Of Risk Factors Of Subjective Cognitive Decline

Objective:Alzheimer’s disease(AD)is a degenerative disease of the central nervous system characterized by progressive cognitive impairment and behavioral damage that occurs in the elderly.Since the disease is incurable,has a high disability rate,and is difficult to care for,families and society pay heavy economic and time costs,early identification of at-risk groups for early prevention is a top priority in the management of AD.However,at present,there is a lack of early identification and diagnosis methods with high sensitivity and specificity.Subjective cognitive decline(SCD)refers to a state in which a person complains of or admits to cognitive impairment but performs normally on a series of cognitive tests,and is considered to be one of the preclinical stages of AD.Surveys have shown that the prevalence of SCD is about 20%in 60-65 year olds and 90%in those over 85 years of age.Previous studies have shown that it takes about 15 years for SCD to progress to Mild cognitive impairment(MCI),and MCI has a 50%chance of progressing to AD within 5years.The establishment of risk factors for SCD as a preclinical stage of AD is an urgent issue at the preventive medicine level.In view of the large number of studies on risk factors for SCD and the different findings,we conducted this systematic review and meta-analysis to assess the intervenable and non-intervenable risk factors for SCD proposed in previous studies and to provide a basis for the prevention and management of SCD.Methods:Searching English databases(Pub Med,EMBASE,Cochrane Library,Web of Science)and Chinese databases(CNKI,Wanfangdata,VIP)for articles published from May 1995 to November 2022.,Screening cross-sectional and cohort studies exploring risk factors associated with SCD.Stata 13.0 was applied to analyze the combined effect size ratio(Odds ratio,OR)and 95%confidence interval(CI)of the included studies.,and the heterogeneity among the studies was assessed by I~2statistic and Q test,and the sources of heterogeneity among the studies were further explored by sensitivity analysis and subgroup analysis.Results:A total of 27 studies were included in the meta-analysis,including 25 cross-sectional studies and 2 cohort studies,containing 432,504 subjects and involving 13risk or protective factors.The results of the quantitative analysis showed that 7 of these factors were associated risk factors for SCD,including advanced age(OR=1.33,95%CI 1.12-1.58,P=0.001),female(OR=1.20,95%CI 1.10-1.31,P<0.001),diabetes(OR=1.46,95%CI 1.21-1.76,P<0.001),hypertension(OR=1.29,95%CI1.08-1.53,P=0.005),anxiety(OR=2.44,95%CI 1.38-4.31,P=0.002),sleep disorder(OR=1.91,95%CI 1.67-2.19,P<0.001),depression(OR=3.31,95%CI 2.67-4.11,P<0.001).Four factors were not associated with SCD,Race(White)(OR=0.95,95%CI 0.76-1.18,P=0.628),living alone(OR=1.21,95%CI 0.95-1.54,P=0.125),smoking(OR=1.18,95%CI 0.97-1.44,P=0.105),alcohol consumption(OR=1.06,95%CI 0.75-1.49,P=0.743).Two factors were protective factors for the occurrence of SCD,including high education(OR=0.61,95%CI 0.52-0.72,P<0.001)and physical exercise(OR=0.57,95%CI 0.48-0.67,P<0.001).Conclusion:(1)Advanced age,female gender,diabetes,hypertension,anxiety,depression and sleep disorders may be risk factors for the development of SCD;(2)High educational level and physical activity may be protective factors for the occurrence of SCD;(3)There is no clear correlation between race(White),living alone,smoking,and alcohol consumption and the occurrence of SCD.