Blood Type & Memory Loss Linked

Previous studies suggested that people with type O blood have a lower risk of heart disease and stroke, factors that can increase the risk of memory loss and dementia. AB is the least common blood type, found in about 4% of the U.S. population.  Mary Cushman, from the University of Vermont College of Medicine (Vermont, USA), and colleagues analyzed data collected in the REasons for Geographic And Racial Differences in Stroke (REGARDS Study) involving over 30,000 people followed for an average of 3.4 years. In those who had no memory or thinking problems at the beginning, the study identified 495 participants who developed thinking and memory problems, or cognitive impairment, during the study. They were compared to 587 people with no cognitive problems.  Compared to people with other blood types, the team found that subjects with AB blood type comprised 6% of the group who developed cognitive impairment, which is higher than the 4% found in the population – equating to an 82% more likely risk for developing the thinking and memory problems that can lead to dementia.  The team then focused on factor VIII, a protein that helps blood to clot, but high levels of which are related to higher risk of cognitive impairment and dementia. People with AB blood had a higher average level of factor VIII than people with other blood types, and subjects in this study with higher levels of factor VIII were 24% more likely to develop thinking and memory problems than people with lower levels of the protein. The study authors write that: “Blood group AB and higher [factor VIII] were associated with increased incidence of cognitive impairment in this prospective study. “