Factors associated with mixed dementia vs Alzheimer disease in elderly Mexican adults

Mixed dementia (DMix) refers to dementia resulting from Alzheimer disease in addition to cerebrovascular disease. The study objectives were to determine the clinical and imaging factors associated with Dmix and compare them to those associated with Alzheimer disease.

Cross-sectional study including 225 subjects aged 65 years and over from a memory clinic in a tertiary hospital in Mexico City. All patients underwent clinical, neuropsychological, and brain imaging studies. We included patients diagnosed with DMix or Alzheimer disease (AD). A multivariate analysis was used to determine factors associated with DMix.

We studied 137 subjects diagnosed with Dmix. Compared to patients with AD, Dmix patients were older and more likely to present diabetes, hypertension, dyslipidaemia, and history of cerebrovascular disease (P<.05). The multivariate analysis showed that hypertension (OR 1.92, CI 1.62-28.82; P=.009), white matter disease (OR 3.61, CI 8.55-159.80; P<.001), and lacunar infarcts (OR 3.35, CI 1.97-412.34; P=.014) were associated with Dmix, whereas a history of successfully treated depression showed an inverse association (OR 0.11, CI 0.02-0-47; P=.004) CONCLUSIONS: DMix may be more frequent than AD. Risk factors such as advanced age and other potentially modifiable factors were associated with this type of dementia. Clinicians should understand and be able to define Dmix.