China: A new study published in the International Journal of Geriatric Psychiatry showed that an inverted U-shaped curve relationship between hemoglobin (HGB) level and overall cognitive profile may exist since both low and high HGB levels might cause cognitive decline in dementia incidence.
Globally, there are around 50 million dementia sufferers, and by 2050, that figure is predicted to quadruple. Anemia has been shown to be a risk factor in relation to hypoxic and oxidative stress, in addition to the well-known risk factors for cognitive decline and dementia (diabetes, dyslipidemia, stroke, smoking, sleep disturbances, alcohol consumption, and decreased cognitive activities). Anemia, which has been linked to worldwide deterioration, a rise in the prevalence of dementia, and worse executive function, affects nearly 20% of people over the age of 65. In order to determine whether there was a relationship between HGB level and cognitive profile and whether it increased the risk of dementia in older people, Yaqi Yang and colleagues undertook this study.

In 2019, a cross-sectional population-based survey with 3,519 participants aged 65 or over was carried out. Basic demographic information was gathered. To examine cognition and HGB level, blood tests and neuropsychological evaluations were used. The non-linear relationship between HGB levels and cognitive function was examined using generalized additive models.
The key highlights of this study were:
1. There were 459 (12.7%) patients who had dementia overall, with more women (54.7%) than men (45.3%).
2. In comparison to those with normal HGB levels, there were more subjects with anemia (3%) and hyperhemoglobinemia (5%) than those without.
3. An inverted U-curve, which is more pronounced in females, may be seen in a graphic representation of the correlation between HGB level and MMSE score.
4. Anemia substantially enhanced the risk of dementia, but not hyperhemoglobinemia, according to logistic regression models.
5. For men and women, these tendencies are not the same.
6. In comparison to patients with normal HGB levels, including males, an abnormal HGB level had a stronger impact on females, increasing the incidence of dementia in females with anemia or hyperhemoglobinemia.
The Authors concluded that both low and high hemoglobin levels are linked to cognitive impairment in the elderly population.
Reference:
Yang, Y., Liu, S., Gan, J., Zhu, H., Du, X., Chen, Z., Ma, L., Meng, Q., Yang, F., Chen, H., & Ji, Y. (2022). Association between hemoglobin level and cognitive profile in old adults: A cross‐sectional survey. In International Journal of Geriatric Psychiatry. Wiley. https://doi.org/10.1002/gps.5806