To the Editor It is often debated whether depression is a risk factor for dementia, whether it is a prodromal state of dementia, or whether depression and dementia share a common underlying pathology, with evidence supporting all these hypotheses. With interest, we read the study of Kaup et al1 that evaluated the risk for dementia associated with different trajectories of depressive symptoms. They identified 3 different 5-year depressive symptom trajectories with latent class growth curve analysis.1 Only persons with high and increasing depressive symptoms had an increased risk for dementia within 11 years, independent from baseline depression severity. The authors concluded that “individuals’ trajectory of depressive symptoms may inform dementia risk above and beyond assessment of depressive symptoms at one time point alone.”1 We would like to discuss another possibility to explore the depression-dementia association in which even a single assessment of depression is sufficient.
Zuidersma M, Oude Voshaar RC. Bifactor Analysis to Disentangle the Depression-Dementia Association. JAMA Psychiatry. 2016;73(11):1201. doi:10.1001/jamapsychiatry.2016.1712