van Dalen JW, et al. - Researchers assessed the correlations between apathy in older dementia-free individuals and incident dementia. They performed a systematic review and meta-analysis of 16 studies including 7,365 patients and identified an approximately doubled risk of incident dementia among memory clinic patients with apathy, depending on age and cognitive function. Findings thereby emphasize the significance of apathy as a relevant, cheap, noninvasive, and easily measureable marker of increased risk of incident dementia with high clinical relevance, particularly because these vulnerable patients may forgo health care.

Methods

• A systematic search of Medline, Embase, and PsychINFO databases was performed by 2 reviewers for prospective cohort studies in general populations or memory clinic patients without dementia with clear definitions of apathy and dementia that reported on the association between apathy and incident dementia.
• PRISMA and MOOSE guidelines were followed for data extraction and synthesis; one reviewer extracted the data and the other checked them.
• Pooled crude risk ratios, maximally adjusted reported hazard ratios (HR), and odds ratios (OR) were assessed as main outcomes and measures using DerSimonian-Laird random effects models.

Results

• The study populations had a mean age ranging from 69.2 to 81.9 years (median, 71.6 years) and the percentage of women ranging from 35% to 70% (median, 53%).
• Researchers included 16 studies comprising 7,365 participants after screening 2,031 titles and abstracts; for 7,299 participants, apathy status was available.
• Populations with subjective cognitive concerns (n = 2), mild cognitive impairment (n = 11), cognitive impairment no dementia (n = 1), or mixed cognitive and no cognitive impairment (n = 2) were included in the studies.
• They identified apathy in 1,470 of 7,299 participants (20.1%).
• Follow-up ranging from 1.2 to 5.4 years was performed.
• Twelve studies used validated apathy definitions; these studies had the combined risk ratio of dementia for patients with apathy of 1.81 (95% CI, 1.32-2.50; I2 = 76%; n = 12), the hazard ratio of 2.39 (95% CI, 1.27-4.51; I2 = 90%; n = 7), and the odds ratio of 17.14 (95% CI, 1.91-154.0; I2 = 60%; n = 2).
• As per subgroup analyses, meta-regression, and individual study, weakening of the association between apathy and dementia was noted with increasing follow-up time, age, and cognitive impairment.
• In patients with mild cognitive impairment, 95% of heterogeneity could be explained by adjusting for apathy definition and duration of follow-up in the meta-regression.