Study Examines Link Between Depression and Dementia

Overview of Research

Recent research published in JAMA Psychiatry explored the relationship between depressive symptoms and dementia diagnoses, concluding that there is no evidence to suggest a link between the two. Conducted by a team from University College London, the study focused on the trajectories of depressive symptoms in relation to subsequent dementia diagnoses.

Study Design and Participants

The research involved 10,189 adults over a span of 28 years, utilizing a regressive study design that began with dementia diagnoses and analyzed participants’ earlier reports on depression-related criteria. The study compared these individuals with those who had depression only, as well as a control group that did not report dementia.

The study, published online in May 2017 in the Journal of the American Medical Association/Psychiatry, included a total of 10,308 participants (67% male, 33% female) aged between 35 and 55 at the time of recruitment for the Whitehall study in 1985. Depressive symptoms were evaluated nine times from 1985 to 2012 using the General Health Questionnaire, with the study concluding in 2015. The incidence of dementia during this period was a primary outcome.

Data Analysis and Findings

The study’s comprehensive data analysis did not differentiate by gender but took into account various factors such as education, socioeconomic status, smoking, alcohol consumption, and personal health conditions. Additionally, it considered participant deaths and whether a dementia diagnosis was received before 2003.

The early-phase assessments took place in 1985, 1989, and 1991, while the later phase occurred in 1997, 2001, and 2003, with follow-up concluding in March 2015. Participants answered 30 questions regarding their experiences of depression, rating their experiences on a scale from “not at all” to “much more than usual.” Their responses were linked to three British national health records documenting dementia diagnoses.

It is important to note that dementia serves as a “preliminary diagnosis,” as a definitive diagnosis can only be confirmed through post-mortem examinations of brain tissue. Alzheimer’s Disease is identified as the most prevalent form of dementia.

Conclusions and Limitations

The results indicated that early reports of chronic depression did not consistently predict dementia diagnoses. A notable strength of the study is its long duration; however, the data did not demonstrate a direct link between depression and future dementia diagnoses.

The researchers acknowledged a limitation in their study, noting the challenge of definitively linking the information in the three British health records with potential underreporting of dementia cases. They emphasized that many individuals with dementia may not have accurately reported their condition in national records.

Author Information

Written by: Susan Mercer Hinrichs, MA, MBA, CPhT