This Common Deficiency May Raise Dementia Risk By 66%, Study Finds

It’s easy to dismiss fatigue as just part of getting older. You sleep a little worse, your energy dips in the afternoon, maybe workouts feel harder than they used to. None of it feels urgent enough to investigate. It just becomes part of daily life, explained away by stress or a busy schedule.

But some of those low-level shifts have less to do with aging itself and are actually signaling abnormalities in your health. For example, blood health rarely enters the conversation unless there’s a clear diagnosis, yet it plays a constant, behind-the-scenes role in how your body functions day to day.

Hemoglobin, the protein that carries oxygen through your bloodstream, doesn’t just influence energy levels. It shapes how well your brain and tissues are actually being supported.

That disconnect between what we feel and what’s happening under the surface is exactly what makes this new research1 worth paying attention to. Instead of focusing on obvious symptoms, it takes a common, often overlooked condition and follows it forward, asking what it might reveal about long-term brain health.

Linking hemoglobin levels to brain health over time

This study followed more than 2,200 adults over the age of 60 who did not have dementia at the start. Researchers measured their hemoglobin levels, which indicate whether someone has anemia, and also looked at a set of blood markers tied to brain health. These markers reflect processes like neuronal damage, inflammation, and early changes associated with Alzheimer’s disease.

Instead of stopping at a single snapshot, the researchers tracked participants for an average of about nine years. During that time, they monitored who went on to develop dementia and how that risk lined up with both hemoglobin levels and those underlying brain biomarkers.

What makes the design compelling is that it connects two layers of information. It doesn’t just ask whether anemia is linked to dementia. It looks at whether anemia is showing up alongside early biological signs of brain changes, long before symptoms appear.

Low hemoglobin, higher dementia risk—and a clue about why

People with anemia had a 66% higher risk of developing dementia over the follow-up period compared to those with normal hemoglobin levels.

But the more revealing detail is what was happening beneath that. Lower hemoglobin levels were also linked to higher levels of key blood markers associated with neurodegeneration. In other words, the same people with anemia were already showing signs of greater stress and damage in the brain.

When those two factors overlapped, anemia plus elevated brain biomarkers, the risk climbed even higher. That suggests anemia may not just be associated with cognitive decline. It may be interacting with the underlying biology that drives it.

One explanation comes down to oxygen. Hemoglobin carries oxygen through the bloodstream, and the brain is one of the most oxygen-dependent organs in the body. When levels are low, the brain may be operating under subtle but chronic stress. Over time, that can contribute to inflammation, oxidative damage, and reduced resilience to other age-related changes.

The pattern was also stronger in men, which raises questions about whether differences in baseline hemoglobin levels or underlying health conditions change how the brain responds to anemia.

What this means for you

Anemia is common, especially with age, and it’s often treatable. Plus, this isn’t about chasing obscure biomarkers. It’s about paying attention to something that’s already easy to measure and, in many cases, modifiable.

Early signs can be easy to overlook. Persistent fatigue, shortness of breath during routine activity, pale skin, or feeling unusually cold can all point to low hemoglobin. Routine blood work usually includes this marker, but it’s worth looking at the number rather than assuming everything is fine if it falls within a broad “normal” range.

Nutrition plays a central role. Iron is the most obvious piece, but it’s not the only one. Vitamin B12, vitamin C, folate, and overall protein intake all support healthy red blood cell production. Beyond diet, factors like chronic inflammation, gut health, and metabolic conditions can also influence how well the body maintains healthy hemoglobin levels.

This doesn’t mean anemia causes dementia on its own. The relationship is more layered than that. But it does suggest that low hemoglobin could be one of the earlier signals that something in the system isn’t working as well as it should.

The takeaway

The takeaway isn’t to worry about every lab value. It’s to recognize that some of the simplest markers can carry more information than we give them credit for. Checking in on your hemoglobin levels and taking small steps to support them may be one of the more straightforward ways to support your long-term brain health.