• This is the first quantitative synthesis estimating the risk of aggressive behaviors in dementia and mild cognitive impairment.
• Individuals with Alzheimer’s disease have five times higher odds of aggression than healthy controls.
• We found no differences in risks of aggression between mild cognitive impairment and normal population controls and between dementias of differing aetiologies.
We aim to estimate the risk of perpetrating aggression in Alzheimer disease (AD) and mild cognitive impairment (MCI) by conducting a systematic review and meta-analysis of primary studies.
A systematic search was conducted in six bibliographic databases according to a preregistered protocol. Studies that reported aggressive behaviors in individuals with AD and MCI compared with healthy individuals or those with other dementia etiologies were identified. Risks of aggressive behaviors were assessed using random effects models to calculate pooled odds ratios (ORs). Publication bias was examined.
In total, 17 studies involving 6,399 individuals with AD and 2,582 with MCI were identified. Compared with healthy individuals, significantly increased risks of aggressive behaviors were found in AD (OR, 4.9, 95% CI, 1.8–13.2) but not in MCI (OR, 1.8, 95% CI, 0.7–4.3). When comparing AD with MCI, the risk in AD was higher (OR, 2.6, 95% CI, 1.7–4.0). We found no differences in risk of aggressive behaviors between AD and other dementia subtypes or between amnestic and nonamnestic MCI.
Individuals with AD are at higher risk of manifesting aggressive behaviors than healthy individuals or those with MCI. Our findings not only underscore the necessity of treatment of aggressive behaviors in AD but also highlight the importance of preventing the transition from MCI to AD.