Objective:

Describe the relationship between persistent and episodic depressive disorders and subsequent diagnoses of Alzheimer’s disease and related dementias (ADRDs).

Background:

Depression is associated with a higher risk of dementia later in life, and previous work shows that multiple episodes of depression increase this risk further. However, limited research exists to determine if this relationship varies between chronic episodic depression (recurrent major depressive disorder) and chronic persistent depression (dysthymia).

Design/Methods:

A retrospective cohort study was conducted via the TriNetX database, which provided access to electronic medical records from 108 healthcare organizations. The analysis examined three ICD-10 codes: F32 (major depressive disorder, single episode), F33 (major depressive disorder, recurrent), F34.1 (dysthymic disorder) within populations aged 18-44. Incidence of unspecified dementia, Alzheimer’s disease, vascular dementia, and frontotemporal dementia were evaluated relative to a control population at any age thereafter. Odds ratio and 95% confidence intervals were determined to assess risk of developing ADRDs by depression diagnosis.

Results:

For those with a single episode of MDD, the greatest risk was observed in the development of vascular dementia (OR= 15.069, CI: (13.159, 17.255)). With recurrent episodes of MDD, significant increases in all four domains were observed. The greatest increase was demonstrated with Alzheimer’s disease (OR= 417.82, CI: (373.785, 460.879)), representing a 76.61x increased odds of disease development relative to those with a single episode of MDD (OR= 5.454, CI: (4.289, 6.936)). The odds ratios of the four dementia domains for dysthymia fell between the odds ratios for single and recurrent episodes of MDD, with vascular dementia posting the greatest risk (OR= 16.178. CI: (12.277, 21.317)).

Conclusions:

The relationship between chronic episodic depression and diagnoses of ADRDs was the strongest across all measured dementia diagnoses, with dysthymia also demonstrating a mediating role in ADRD development.