OBJECTIVES: Alzheimer’s disease (AD) is the most common neurodegenerative disease worldwide. We conducted a systematic literature review to assess the impact and burden of AD.

METHODS: Searches of Embase, MEDLINE and the Cochrane Library (conducted on 7 August 2020; updated on 10 November 2021) identified observational studies (published 2010–2021 in any country) reporting incidence, prevalence, comorbidities and/or outcomes related to disability, mortality and life expectancy, in patients with mild cognitive impairment (MCI) due to AD, or mild, moderate or severe AD dementia.

RESULTS: Overall, 71 studies, mostly from Europe, the USA and Asia, met the inclusion criteria; 45 reported data on incidence/prevalence, 28 on comorbidities and 26 on mortality-/disability-related outcomes. Incidence and prevalence estimates varied widely. Two studies found that mild dementia was the most prevalent stage of AD dementia, and one found that moderate dementia was slightly more prevalent. The most commonly reported comorbidities in the available evidence were hypertension, cardiovascular disease and diabetes. Two studies compared comorbidity prevalence between patients with AD dementia and age- and sex-matched controls: one found higher comorbidity prevalence in AD dementia, and one found a higher prevalence of diabetes only. In one study, AD dementia accounted for the largest proportion of disability-adjusted life-years (33%) and years lived with disability (37%) attributed to all-cause MCI and all-cause dementia. Among patients with AD dementia, older age, male sex, a higher comorbidity burden, lower cognitive test scores and higher tau levels in cerebrospinal fluid predicted greater mortality. One study found that 5-year mortality in patients with AD dementia was double that in the age- and year-matched general population.

CONCLUSIONS: Available studies suggest that patients with AD may experience more comorbidities, greater disability and greater mortality than the general elderly population. However, further studies quantifying the impact of AD are needed to inform care and policy.