Brain Imaging Technique May Predict Dementia Risk

A novel brain imaging method might be able to forecast whether someone will face dementia later in life, according to a recent study.

Researchers at Johns Hopkins University employed a specialized MRI technique known as quantitative susceptibility mapping (QSM) during a long-term study aimed at measuring iron levels in the brain.

Alzheimer’s disease, which affects around 7 million Americans and is the foremost cause of dementia, is believed to stem from the buildup of damaging amyloid plaques and tau proteins that interfere with brain cell functionality and disrupt neuron communication.

However, scientists are now exploring how increased iron levels in the brain could affect cognitive abilities.

This concept of “iron overload,” where mineral levels are abnormally high, disrupts the balance between harmful free radicals and antioxidants. This can accelerate nerve cell death.

Traditionally, iron levels in the brain are assessed post-mortem through brain tissue samples. In contrast, QSM enables scientists to non-invasively gauge these levels while a patient is alive.

In the study, researchers evaluated QSM MRI data from 158 cognitively healthy participants, establishing baseline iron levels for each. Over a period of 7.7 years, they collected updated readings.

Results indicated that higher initial readings of brain iron, particularly in regions critical for memory and cognitive function, were linked to a greater risk of developing mild cognitive impairment in the future.

This transitional stage can precede dementia related to Alzheimer’s disease.

The researchers believe their findings underscore the potential of QSM as a non-invasive diagnostic tool, enabling the identification of abnormal iron levels that may indicate disease progression prior to symptom onset. 

This could pave the way for earlier detection and more targeted interventions.

While there isn’t a universally “normal” level of brain iron, since it varies by brain region and tends to increase with age, typical ranges exist for particular areas.

Currently, there isn’t a cure for dementia or Alzheimer’s, but the study team suggests that clinical trials could be designed to explore iron-targeted therapies.

Dr. Xu Li, the senior author and an associate professor of radiology at Johns Hopkins University, remarked, “QSM can detect subtle differences in iron levels across various brain regions. This offers a reliable, non-invasive approach to mapping and quantifying iron in patients – which isn’t possible with traditional MR techniques.

“Through QSM, we observed increased brain iron in certain memory-related areas associated with a heightened risk of cognitive impairment and more rapid decline.”

“Using this tool, we can better identify individuals at high risk for Alzheimer’s disease and potentially guide early interventions when new treatments are available.”

Moreover, beyond its role as a biomarker, brain iron might become a future therapeutic target.

The researchers aim to refine QSM technology, making it quicker and more accessible in clinical settings.

The study’s results were published in the journal Radiology.

Notably, high iron levels in Alzheimer’s patients were first reported in an autopsy study back in 1953.

Iron is essential for many biochemical processes in the body, including oxygen transport and DNA synthesis. The body derives iron from various food sources, with red meat being particularly rich, and absorbs it through the small intestine.

A delicate balance of iron is crucial in the brain; both deficits and excesses can have harmful effects.

Abnormal iron buildup has been observed in several neurodegenerative diseases, such as Parkinson’s and Huntington’s, though it’s unclear if this accumulation is a direct cause or a secondary effect.

Earlier research has found correlations between iron accumulation and amyloid beta, a protein that clusters in the brains of individuals with Alzheimer’s and forms disruptive plaques between neurons.

Similar associations have also been recognized between iron and neurofibrillary tangles—abnormal aggregations of tau protein inside neurons that hinder their transport systems and impair communication.

Evidence also suggests that deep grey matter in Alzheimer’s patients holds higher concentrations of iron, which is crucial for normal neural activity and central nervous system function.

Less is known about the neocortex, the outer layer of the brain involved in language, conscious thought, and other critical functions.

Impaired iron regulation in individuals with Alzheimer’s suggests that iron chelation therapy, which uses drugs to reduce iron levels through urine excretion, may be a promising avenue for treatment in clinical trials.