Depression can look starkly different for everyone — but 6 symptoms could increase dementia risk

By Katia Hetter, CNN

(CNN) — We often discuss depression and dementia separately, although scientists have long observed a connection between the two: People with depression appear to have a higher likelihood of developing dementia later in life.

A new study published in The Lancet Psychiatry adds an important twist in untangling that relationship and looks beyond depression as a single diagnosis. By focusing on specific symptoms, the research raises a more precise and potentially more useful question: Could certain symptoms in midlife signal greater vulnerability to dementia decades later? And if so, what should people and clinicians do with that information now?

To guide us through this topic, I spoke with CNN wellness expert Dr. Leana Wen. She is an emergency physician and clinical associate professor at George Washington University. Wen previously was Baltimore’s health commissioner.

CNN: What did this new study examine, and why did researchers focus on individual depressive symptoms instead of depression overall?

Dr. Leana Wen: The researchers wanted to answer a specific question: When studies find that depression is linked to dementia, is the risk tied to depression as a broad diagnosis or, potentially, a smaller set of specific symptoms within depression?

To answer this question, they analyzed data from a long-running British study that began decades ago. Over 5,800 adults completed a 30-item questionnaire about depressive symptoms in the late 1990s, when all participants were dementia-free. Participants were then followed for about 25 years through national health registries, with dementia diagnoses tracked up to 2023. Over that follow-up period, about 10% of participants developed dementia.

CNN: Which symptoms did the researchers examine, and how do these differ from one another?

Wen: The study identified six symptoms that are especially correlated with dementia risk years later. They are: losing confidence in oneself; not being able to face up to problems; not feeling warmth and affection for others; feeling nervous and anxious all the time; not being satisfied with the way tasks are carried out; and difficulties concentrating.

These symptoms do not all point to the same experience. Some relate to self-perception and coping, such as losing confidence or not being able to face problems. Others speak to connection and emotional engagement, such as not feeling warmth or affection. Others are more about sustained anxiety or tension, such as feeling nervous and strung up. And some relate to how the brain is functioning day to day, such as difficulty concentrating or a sense of dissatisfaction with how tasks are carried out.

That is one reason this symptom-level approach is helpful. Depression is not one uniform experience. People can share the same diagnosis but have very different symptom patterns, and this study suggests those patterns may not all have the same relationship to later cognitive health.

CNN: Why might some depressive symptoms be linked to later dementia risk while others are not?

Wen: There are a few plausible explanations, and it is important to say up front that these are hypotheses rather than proof. This was an observational study, so it can point to possible links but not necessarily establish why those associations exist.

One possibility is that some symptoms are more likely to lead to behavioral changes that affect brain health over time. For example, loss of confidence, difficulty coping with problems and trouble concentrating can make people reduce social engagement or stop doing things that provide mental stimulation. If certain symptoms push people toward isolation and disengagement, that could increase dementia risk.

Another possibility is that some symptoms may reflect early changes in brain function that are not yet diagnosed as dementia but could be related to the same underlying processes. And a third is that there may be similar underlying risk factors. For instance, chronic stress, poor sleep and other chronic disease risk factors can influence both mood and cognition.

The study attempted to account for established risk factors, but no study can perfectly separate every pathway. The take-home point is that the relationship between depression and dementia likely is not one single pathway, and symptom-level patterns may help researchers narrow where to look.

CNN: What does “midlife” mean in this study, and why is this period important for brain health?

Wen: In this study, the participants were ages 45 to 69 at the time depressive symptoms were measured, with an average age of about 55. That timing is important because dementia is typically diagnosed much later, but the biological and social factors that influence risk can start accumulating decades earlier.

Midlife is also a period when many modifiable risk factors become more prominent. Blood pressure rises for many people. Weight gain and insulin resistance can increase. Sleep can worsen. Chronic stress can accumulate. At the same time, midlife is a key window for prevention. If researchers can identify signals that suggest elevated risk years before dementia develops, that creates an opportunity to intervene earlier.

CNN: Does this research suggest that depression causes dementia? Should people experiencing these symptoms be concerned about their future cognitive health?

Wen: This research does not show that depression causes dementia, and it certainly does not mean that someone with these symptoms is destined to develop dementia. It shows a possible association: Certain symptoms reported in midlife were linked to a higher likelihood of later dementia in this cohort.

The takeaway for people who may experience one or more of these symptoms is not alarm, but attention. They may consider seeking care because these symptoms affect daily life and well-being in the present. An additional reason for considering care is the implications for longer-term brain health.

CNN: What are other steps can people take in midlife to support brain health and potentially reduce dementia risk?

Wen: Focus on several changes that repeatedly show up in dementia prevention research.

First, protect cardiovascular health. Brain health depends on healthy blood flow. Managing blood pressure, cholesterol and blood sugar matters, as does maintaining a healthy weight, regular physical activity and good nutrition.

Second, prioritize sleep. Chronic poor sleep affects mood and cognitive function and is linked to long-term cognitive risk.

Third, invest in social connection and cognitive engagement. That investment does not have to mean big changes. It can be regular time with friends or family, volunteering, taking a class or returning to hobbies that involve learning and interaction.

Fourth, do not overlook hearing and vision. Treatable sensory loss often contributes to social isolation, and correcting it can make it easier to stay connected and engaged.

Finally, treat depression and other mental health issues directly. If symptoms are present, talk with a primary health physician or mental health provider. This study underscores that symptoms in midlife may be more meaningful than we once thought, and it adds another reason to take mental health seriously as part of long-term overall health.

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