A new study has linked low and high haemoglobin levels to an increased risk of developing dementia in the future.
The study titled ‘Haemoglobin and anaemia in relation to dementia risk and accompanying changes on brain MRI’ was published in the July 31, 2019, online issue of Neurology .
The study involved 12,305 people with an average age of 65 who did not have dementia. Overall, 745 (6%) of the study subjects were found to have anaemia. The researchers followed the participants for an average of 12 years. During that time, 1,520 people developed dementia. Of these, 1,194 had Alzheimer’s.
Subjects who had anaemia were 41% more likely to develop Alzheimer’s and 34% more likely to develop any type of dementia compared to those who did not have anaemia. Of the 745 people with anaemia, 128 developed dementia compared to 1,392 of the 11,560 who did not have anaemia.
Similarly, participants with high haemoglobin levels were also more likely to develop dementia. The participants were divided into five groups based on their haemoglobin levels. Compared to the middle group, the group with the highest haemoglobin levels was 20% more likely to develop dementia. Those in the lowest group were 29% more likely to develop dementia than those in the middle group, according to the study.
The findings should ring a warning bell for developing countries, including India, said Bengaluru-based doctors. “In terms of public health importance, the association with anaemia is more relevant for our setting as it is very common in the elderly and particularly those with poor socio-economic status. The study confirmed the previously known relationship of anaemia and increased risk for dementia with a more rigorous methodology,” said P.T. Sivakumar, professor of psychiatry and consultant in geriatric psychiatry unit, Department of Psychiatry, NIMHANS. “Previous studies that had shown this relationship did not rule out the possibility that it could be due to nutritional impairment in early stages of cognitive decline and dementia. This study emphasises the need for screening and treatment of anaemia to reduce the risk as this is a potentially modifiable risk factor,” Dr. Sivakumar said.
Needs further research
On the high levels of haemoglobin also linked to dementia, he said: “This is possible as high haemoglobin level can affect blood flow and oxygen delivery to tissues. However, this needs further evaluation.” Arvind Kasthuri, professor of community health and coordinator of senior citizens health service at St John’s Medical College, said the mechanisms used to link high haemoglobin levels with increased risk of dementia are not clear and hypothetical in the study. “This needs to be further studied. Anaemia is a risk factor for many conditions including dementia. A disciplined lifestyle that includes exercise, low-cholesterol and high-fibre diet, and engaging in cognitive activities is important to prevent cognitive decline,” he added.
