Utilizing apolipoprotein E genotypes and associated comorbidities for the assessment of the risk for dementia

Introduction Dementia is associated with many comorbidities while being related to Apolipoprotein E (ApoE) polymorphism. However, it is unclear how these clinical illnesses and genetic factors modify the dementia risk. Methods We enrolled 600 dementia cases and 6000 matched non-dementia controls, with identified ApoE genotype (epsilon 4/epsilon 4, epsilon 4/epsilon 3, and epsilon 3/epsilon 3). Eight comorbidities were selected by medical records, and counted if occurring within 3 years of enrollment. Results The dementia group had a higher ratio of carrying epsilon 4 allele and prevalence of comorbidities than the non-dementia group. Homozygous epsilon 4 carriers presented the broken line of dementia risk with the peak age at 65-75 years and odds ratio (OR) up to 6.6. The risk only emerged after 65 years of age in epsilon 3/epsilon 4 subjects with OR around 1.6-2.4 when aged > 75 years. Cerebrovascular accident (CVA) is the commonest comorbidity (14.6%). CVA, sleep disorder, and functional gastrointestinal disorders remained as significant risk comorbidities for dementia throughout all age groups (OR = 1.7-5.0). When functional gastrointestinal disorder and epsilon 4 allele both occurred, the dementia risk exceeded the summation of individual risks (OR = 3.7 and 1.9 individually, OR = 6.0 for the combination). Comorbidities could also be predictors of dementia. Conclusion Combining the genetic and clinical information, we detected cognitive decline and optimize interventions early when the patients present a specific illness in a particular age and carry a specific ApoE allele. Of comorbidities, functional gastrointestinal disorder is the strongest predicting factor for dementia in epsilon 4 allele carriers.

Automated summary

This study found that dementia is associated with many comorbidities and Apolipoprotein E (ApoE) polymorphism. Homozygous epsilon 4 carriers have a higher risk of dementia, with the peak age at 65-75 years. Cerebrovascular accident, sleep disorder, and functional gastrointestinal disorders are significantly associated with dementia.