OBJECTIVES: Depression is associated with an increased dementia risk in late life, and a couple of pieces of literature suggest an association between depression and dementia, but the nature of the association in the long term remains unresolved. Using the Alzheimer's Disease Neuroimaging Initiative database (ADNI), we wanted to see if there is an association between developing Alzheimer's disease and related dementias (ADRD) and a history of depression.

METHODS: We conducted a national cohort study of 1,033 unique patients, whose data were collected by ADNI. Univariate analyses included examination of an association between ADRD and independent or predictor variables using chi-square tests for categorical variables and two sample t-tests for quantitative continuous variables. A multiple-variable logistic regression will be used to assess the association between dependent and multiple independent variables. Five models were fit to evaluate both confounding with the primary independent variable and model goodness-of-fit for prediction of ADRD. We used the Akaike Information Criterion (AIC) as the goodness-of-fit metric, a log likelihood-based metric that penalizes for the number of parameters in the model.

RESULTS: The multiple logistic regression analysis showed that there is an association between developing ADRD and having a history of depression, as the odds ratio is below 1. Participants without ADRD were less likely to have a history of depression compared to participants with ADRD. Adjusted covariates had nearly no effect on the association between ADRD and depression.

CONCLUSIONS: In conclusion, our analysis showed that participants with a history of depression are more likely to develop ADRD compared to participants with a healthy mental status. Further research among a larger sample of participants is required to improve the external validity of these findings.