Background: There is rapid growth of older people in Low- and Middle- Income Countries (LMICs). The aim of this review was to assess the literature on prevalence of anxiety and depression in this demographic, which to our knowledge, has not yet been conducted.

Methods: Databases including Medline, PsychInfo, Embase, Scielo and African Journals Online were searched for terms including "mental disorders", "neurotic disorders", "mood disorders" and "anxiety disorders". Studies published between 1990 and 2020 providing data on older people (≥50 years) in LMICs (defined by World Bank Criteria) were included and quality-assessed. Meta-analysis was conducted on a subset of higher-quality studies to derive pooled prevalence estimates of depression.

Results: One hundred and forty relevant studies were identified, of which thirty-two were included in meta-analysis. One hundred and fifteen studies reported depression prevalence only, 19 reported both depression and anxiety, and six reported anxiety only. In all studies identified, depression prevalence ranged from 0.5 % to 62.7 %, and Generalised Anxiety Disorder prevalence ranged from 0.2 % to 32.2 %. The pooled prevalence of depression on meta-analysis was 10.5 % (95 % CI, 8.9 % - 11.2 %). Reported prevalence rates of depression were significantly different in studies using ICD-10 compared with DSM criteria, and between community and clinical settings.

Limitations: The search strategy contained bias towards English language papers and high income country (HIC) publications. There is significant heterogeneity within the meta-analysis.

Discussion: A wide range of methodologies and clinical criteria are used in prevalence studies of depression and anxiety in older people. Studies using screening tools found higher prevalence rates; clinicians and researchers should ensure diagnosis is made with gold-standard clinical criteria. Meta-analysis data suggest that rates of depression are similar in older people in LMICs compared to HICs but mental healthcare resources are limited, suggesting a large potential treatment gap.