Summary: Symptomatic depression is linked to a 51% greater risk of developing dementia, but patients who received treatment for depression showed a substantially lower likelihood of later dementia diagnosis.
Source: Elsevier
Depression has long been observed to increase the risk of dementia. A new prospective cohort study now suggests that timely and effective treatment of depression may reduce that risk in specific groups of patients.
More than 55 million people worldwide live with dementia, a progressive neurocognitive condition that primarily affects older adults and has no cure. Identifying modifiable factors that can delay onset or reduce risk is critical to lowering the global burden of the condition.
The study was led by Jin-Tai Yu, MD, PhD, of Huashan Hospital, Shanghai Medical College, Fudan University, and Wei Cheng, PhD, of the Institute of Science and Technology for Brain-Inspired Intelligence at Fudan University, Shanghai, China, and was published in Biological Psychiatry.
Using data from the UK Biobank, a large population-based cohort of more than 500,000 participants, the research team analyzed health records and follow-up data for 354,313 adults aged 50 to 70 at baseline. The analysis included more than 46,000 participants identified with depression and tracked dementia diagnoses over a follow-up period that extended through 2020.
Previous research into whether depression treatments—such as antidepressant medication and psychotherapy—can lower dementia risk has produced mixed results. This study sought to clarify the relationship by accounting for differences in how depressive symptoms change over time within individuals.
“Older adults can show very different patterns of depressive symptoms as years go by,” said Professor Yu. “Those within-person symptom trajectories may carry distinct risks for dementia and may also respond differently to treatment.”
To capture that heterogeneity, participants with depression were classified into one of four symptom-course patterns: an increasing course (mild symptoms that worsen over time); a decreasing course (initial moderate-to-severe symptoms that improve); a chronically high course (persistent severe symptoms); and a chronically low course (ongoing mild or moderate symptoms).
Overall, the study found that depression increased the risk of developing dementia by 51% compared with participants without depression. However, the risk varied by depressive-course pattern: the increasing, chronically high, and chronically low courses were associated with higher dementia risk, while the decreasing course showed no increased risk relative to non-depressed participants.
The investigators then examined whether receiving treatment for depression altered dementia risk. Across the depressed group as a whole, those who received treatment had an approximately 30% lower risk of developing dementia compared with depressed individuals who were untreated.
When the researchers analyzed treatment effects within each depression-course subgroup, benefits were not uniform. Participants with increasing symptoms and those with chronically low symptoms experienced meaningful reductions in dementia risk when treated, while those with a chronically high course of depressive symptoms did not show a significant treatment-related reduction in dementia risk.
“These findings reinforce that poorly controlled or long-standing depressive symptoms carry substantial medical risk,” said Biological Psychiatry editor John Krystal, MD. “Symptomatic depression was linked to a 51% higher dementia risk in this cohort, and treatment was associated with a significant reduction in that risk for many patients.”
Professor Cheng emphasized the clinical implications: “Timely treatment for late-life depression may not only relieve mood symptoms but could also delay the onset of dementia for some patients. The results underscore the need for early intervention before depression progresses to a chronically severe state.”
The pattern-specific differences in treatment effectiveness may help explain why earlier studies reported inconsistent results. By distinguishing symptom trajectories, this study provides a more nuanced view of when depression treatment is most likely to reduce dementia risk.
About this depression and dementia research news
Author: Eileen Leahy
Source: Elsevier
Contact: Eileen Leahy – Elsevier
Image: The image is in the public domain
Original Research: Closed access.
“Depression, Depression Treatments, and Risk of Incident Dementia: A Prospective Cohort Study of 354,313 Participants” by Wei Cheng et al. Biological Psychiatry
Abstract
Depression, Depression Treatments, and Risk of Incident Dementia: A Prospective Cohort Study of 354,313 Participants
BACKGROUND
This study investigated how different longitudinal courses of depressive symptoms and the use of depression treatments relate to the risk of developing incident dementia.
METHODS
In this prospective cohort study, 354,313 UK Biobank participants aged 50 to 70 were recruited between 2006 and 2010 and followed through 2020, totaling over 4.2 million person-years. The researchers first assessed dementia incidence across four symptom-course subgroups. Among participants with depression—approximately 46,000—cases were categorized as treated or untreated, and survival analyses compared dementia risk across treatment groups and symptom-course subtypes.
RESULTS
Depression was associated with a 51% increased risk of dementia overall. The increasing, chronically high, and chronically low symptom courses were linked to higher dementia risk, while the decreasing course showed no association. Compared with untreated depressed participants, those who received treatment had a hazard ratio of 0.7 (95% CI = 0.62–0.77) for incident dementia. Treatment was associated with a 42% lower dementia risk in the increasing-symptom group and a 29% lower risk in the chronically low group, whereas no significant reduction was observed for the chronically high group.
CONCLUSIONS
The study supports a link between depression treatment and reduced dementia risk in specific symptom-course groups, emphasizing the importance of timely interventions before depressive symptoms become chronically severe. Targeted treatment strategies for late-life depression may help reduce future dementia incidence in vulnerable subgroups.