For decades, there have been indications that there is a link between increased iron levels in the brain and Alzheimer’s disease. Leiden physicists find this connection as well, thereby now making a distinction between different forms of iron. They identify specific iron forms that increase in Alzheimer’s patients. Publication in Scientific Reports.

Iron plays an important role in various biological processes, including processes in the human brain. With cerebral disorders such as Alzheimer's disease there are indications that the iron balance is disturbed, because researchers measure an increased iron content. For this, scientists use an MRI scanner, which measures the content indirectly. But this way the different types of iron remain invisible, while they would provide extra information, among other things about the disease stage—the Braak stage.

Iron forms
Lucia Bossoni from the Leiden Institute of Physics and the Leiden University Medical Center and her colleagues have now combined MRI with other techniques called EPR and SQUID magnetometry. This enables them to distinguish different shapes in which iron occurs. They confirm previous studies that establish a link between increased iron content and Alzheimer's disease, while making this connection specific for individual iron forms. For example, the iron concentration in the mineral ferrihydrite is higher in the group of Alzheimer’s patients than in the control group (see figure).

Difference between the group of Alzheimers’s patients (red) and the control group (blue) in the magnetic moment of magnetite (left) and the iron concentration in ferrihydrite (right). Both are generally larger in the group of Alzheimer’s patients.

Braak stage
In addition, Bossoni spots a trend where certain iron forms correlate with the Braak stage. The iron concentration in the protein ferritin and the magnetic moment of the mineral magnetite appear to increase as Alzheimer's disease reaches a more advanced stage. Bossoni: 'When we talk about iron increase in connection with neurodegenerative diseases, we have to pay extra attention to the specific iron form that really matters.'

Publication
Marjolein Bulk, Louise van der Weerd, Wico Breimer, Nikita Lebedev, Andrew Webb, Jelle J. Goeman, Roberta J. Ward, Martina Huber, Tjerk H. Oosterkamp & Lucia Bossoni, ‘Quantitative comparison of different iron forms in the temporal cortex of Alzheimer patients and control subjects’, Scientific Reports