New imaging research is offering detailed insights into the relationship between Alzheimer’s disease and abnormal accumulations of iron in the brain. The study confirms a distinct correlation between higher iron deposits in particular brain regions and rates of cognitive decline.
A small, but growing, body of evidence is suggesting heightened levels of iron in the brain can be linked with other pathological signs of Alzheimer’s disease, including toxic aggregations of amyloid and tau proteins. A study published last year examining post-mortem brain samples of Alzheimer’s patients found significantly elevated cortical iron levels correlating with the severity of a patient’s symptoms. Another more recent brain imaging study found a strong relationship between tau proteins misfolding, iron accumulation and neurodegeneration.
Now a new study from a team of European researchers presents a novel MRI approach to measuring brain iron levels, offering the clearest indication to date of the relationship between Alzheimer’s-related cognitive decline and neural iron deposits.
The researchers imaged 100 subjects with Alzheimer’s, compared to 100 age-matched healthy controls. Around half of the Alzheimer’s cohort were followed for 17 months to evaluate the correlation between cognitive decline and increasing brain iron levels. Co-author on the study, Reinhold Schmidt, says this study found significant iron accumulations in the neocortex and deep gray matter.
"We found indications of higher iron deposition in the deep gray matter and total neocortex, and regionally in temporal and occipital lobes, in Alzheimer's disease patients compared with age-matched healthy individuals," says Schmidt.
Schmidt notes the longitudinal data shows brain iron levels increasing in the temporal lobes as cognitive decline progresses. This is not evidence iron accumulation necessarily plays a causal role in cognitive decline, but does indicate a relationship between the two factors.
It is still unclear whether targeting these iron deposits could offer beneficial therapeutic outcomes for patients with Alzheimer’s. However, the study does show that iron levels in certain parts of the brain may be a useful diagnostic marker to track the neurodegeneration associated with Alzheimer’s.
"Our study provides support for the hypothesis of impaired iron homeostasis in Alzheimer's disease and indicates that the use of iron chelators in clinical trials might be a promising treatment target," says Schmidt. "MRI-based iron mapping could be used as a biomarker for Alzheimer's disease prediction and as a tool to monitor treatment response in therapeutic studies."
The new study was published in the journal Radiology.