Dementia risk is increased by even mild anemia

Dementia is afflicting a third of the senior adults in the US according to recent statistics. Anemia, even mild anemia, by diminishing oxygen perfusion in the brain that neurons require to function and survive increases the risk of dementia according to a study just published in the journal Neurology. The authors designed their study to...

"...determine whether anemia is associated with incident dementia in older adults."

Their subjects were 2,552 older adults (who were free of dementia at the start. Of particular importance is that they defined anemia using the WHO criteria of a hemoglobin concentration less than 13 g/dL for men and less 12 g/dL for women. This was correlated with subsequent dementia diagnoses to determine the hazard for developing dementia associated with anemia. Their data supported an association consistent with the biological hypothesis:

"Of 2,552 participants, 392 (15.4%) older adults had anemia at baseline. Over 11 years of follow-up, 455 (17.8%) participants developed dementia. In the unadjusted model, those with baseline anemia had an increased risk of dementia (23% vs 17%, hazard ratio = 1.64) compared to those without anemia. The association remained significant after adjusting for demographics, APOE ε4, baseline 3MS score, comorbidities, and renal function. Additional adjustment for other anemia measures (mean corpuscular volume, red cell distribution width), erythropoietin, and C-reactive protein did not appreciably change the results. There was no interaction by sex and race on risk of developing dementia."

Clinical note: I want to draw particular attention to the WHO criteria that establish a diagnosis of anemia for men and women when hemoglobin is less than 13 g/dL and 12 g/dL for men and women respectively. I frequently see lab reports that accept significantly lower values as normal, causing practitioners to overlook a very important point for case management of a wide range of condiitons—whether the effect is due to diminished oxygen delivery to tissues or the deleterious effect of the underlying causes of the anemia itself. I prefer to see hemoglobin at least 14.0 for men and 13.5 for women because even borderline anemia can have significant consequences. The authors conclude:

"Among older adults, anemia is associated with an increased risk of developing dementia. Findings suggest that further study of anemia as a risk factor for dementia and a target for intervention for cognitive health is warranted."