Frequency and Associated Factors of Mild Behavioural Impairment and Domains in Patients With Subjective Cognitive Decline: A Systematic Review With Meta‐Analysis and Meta‐Regression

Mild behavioural impairment (MBI) and subjective cognitive decline (SCD) are both associated with an increased risk of dementia and may serve as early clinical markers of neurodegeneration. However, the prevalence and clinical relevance of MBI in individuals with SCD remain unclear. We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines. MEDLINE, EMBASE and PsycINFO were searched for studies evaluating the prevalence of MBI in SCD using validated instruments. A random effects meta-analysis was performed to estimate pooled prevalence, and meta-regression was conducted to explore sources of heterogeneity. Thirteen studies were included in the systematic review, with nine contributing to the meta-analysis. The pooled prevalence of MBI in SCD was 33% (95% CI: 18%-51%, I² = 93%). Subgroup analysis showed a prevalence of 24% in studies using the MBI Checklist (MBI-C) and 50% in those using the Neuropsychiatric Inventory Questionnaire (NPI-Q). Two studies compared individuals with SCD to cognitively normal participants, suggesting a higher frequency of MBI in the SCD group; however, due to the small number of studies, this comparison was described narratively rather than analysed quantitatively. In contrast, patients with mild cognitive impairment (MCI) were significantly more likely to exhibit MBI than those with SCD (OR = 1.92, 95% CI: 1.23-2.99, I² = 50%). Longitudinal studies suggested that MBI is associated with an increased risk of cognitive decline and dementia. Methodological differences in MBI assessment were the main source of heterogeneity across studies. MBI is frequent in SCD and may serve as a relevant clinical marker for identifying individuals at increased risk of cognitive decline. Early recognition may improve risk stratification and inform preventive strategies. PROSPERO: CRD42024616104.