Eating red meat may increase Alzheimer's risk
If you’re a red meat lover, you may be increasing your risk of developing Alzheimer’s disease, according to a new study published in the Journal of Alzheimer’s Disease.
As researchers from the Semel Institute for Neuroscience and Human Behavior at UCLA explained, eating too much red meat increases iron levels in the brain, which can hasten the damaging reactions of free radicals.
Over time, iron accumulates in gray matter regions of the brain, further raising the risk of developing Alzheimer's and other age-related illnesses, such as dementia.
According to the Alzheimer’s Association, memory loss is mild in the early stages. But with late-stage Alzheimer's, individuals lose the ability to carry on a conversation and respond to their environment.
Most Alzheimer’s experts agree that it is caused by one of two proteins: 1) Tau; and 2) Beta-amyloid. As we age, these two proteins either disrupt communication between neurons in the brain, or they kill them off.
However, researchers involved in this study, including team leader Dr. George Bartzokis, believe that iron build up is a third likely cause of Alzheimer's.
Dr. Bartzokis and his team used sophisticated high- and low-field strength MRI brain-imaging instruments to compare the hippocampus and the thalamus of the brain. In Alzheimer’s patients, the hippocampus is damaged early on, but the thalamus doesn’t suffer damage until the late stages of the disease.
This was evidenced by the MRI scans that revealed iron accumulated over time in the hippocampus, but not in the thalamus. The research team also saw a link between iron accumulation in the hippocampus and tissue damage in that region.
Although scientists do not know exactly what causes cell death and tissue loss in the Alzheimer's brain, prime suspects are plaques and tangles. Tangles are strands of twisted proteins.
Most researchers concentrate on the accumulation of two proteins, beta-amyloid or tau, both of which cause the tell-tale plaques associated with Alzheimer’s. But for a long time, Bartzokis had been saying that the breakdown starts off much further "upstream".
As Bartzokis explained, communication between neurons is disrupted when myelin, a fatty tissue in the brain, is destroyed. Myelin coats nerve fibers, stimulating the build-up of amyloid plaques that, in turn, destroy more myelin in a vicious cycle of destruction. The more the brain's neurons get disrupted over time, the more the nerve cells are destroyed; thus, resulting in the classic signs of Alzheimer's.
He added that myelin is produced by oligodendrocytes, which are a type of brain cell that, along with myelin, have the highest iron levels of any brain cells.
"Circumstantial evidence has long supported the possibility that brain iron levels might be a risk factor for age-related diseases like Alzheimer's," says Bartzokis.
While iron is crucial for cell function, too much of it promotes oxidative damage, which the brain is especially susceptible to. Accordingly, Bartzokis and his colleagues wanted to find out if high tissue iron might play a role in causing the tissue breakdown associated with Alzheimer's.
The study included 31 Alzheimer's patients and 68 healthy individuals of the same age as controls. The research team focused on the hippocampus, the brain region involved in the formation of memories, comparing the hippocampus to the thalamus, a region of the brain that, unlike the hippocampus, remains mostly unaffected until the very late stages of the Alzheimer’s.
During the MRI, the researchers measured the amount of iron in the brain that was stored inside a protein – ferritin. However, Bartzokis pointed out that measuring iron can be difficult in Alzheimer's patients, as the amount of water in their brains increases with the progression of the disease.
"It is difficult to measure iron in tissue when the tissue is already damaged. But the MRI technology we used in this study allowed us to determine that the increase in iron is occurring together with the tissue damage,” Bartzokis said.
“We found that the amount of iron is increased in the hippocampus and is associated with tissue damage in patients with Alzheimer's but not in the healthy older individuals - or in the thalamus. So the results suggest that iron accumulation may indeed contribute to the cause of Alzheimer's disease," he added.
The research team also reported that the accumulation of iron in the brain could be due to environmental factors, such as the amount of red meat consumed, iron supplements taken, or whether a female patient had a hysterectomy prior to menopause (because such procedure is known to increase iron levels in the brain).
"The data shows that in AD, Hipp damage occurs in conjunction with ferritin iron accumulation. Prospective studies are needed to evaluate how increasing iron levels may influence the trajectory of tissue damage and cognitive and pathologic manifestations of AD," the researchers concluded.
Meanwhile, in another study published in the March 2013 issue of the Journal of Alzheimer's Disease, researchers from Case Western Reserve University in Cleveland reported that an iron imbalance caused by prion proteins collecting in the brain, is probably the cause of cell death in Creutzfeldt-Jakob disease, or CJD.
The Cleveland research team added that certain proteins detected in the brains of patients with Alzheimer's and Parkinson's also regulate iron, which they say suggests that "neurotoxicity by the form of iron, called redox-active iron, may be a trait of neurodegenerative conditions in all three diseases."
"There are many skeptics who think iron is a bystander or end-product of neuronal death and has no role to play in neurodegenerative conditions,” said study leader Neena Singh. “We're not saying that iron imbalance is the only cause, but failure to maintain stable levels of iron in the brain appears to contribute significantly to neuronal death."
Alzheimer’s is a progressive disease that has become increasingly prevalent over the years. It is the sixth leading cause of death in the United States and starts off with symptoms of dementia that gradually worsen over a number of years.
Those with Alzheimer's live an average of eight years after their symptoms become noticeable to others, but survival can range from four to 20 years, depending on age and other health conditions. To date, there have been very few effective treatments for Alzheimer's disease, which further proves the disease is an extremely challenging one to battle.
SOURCE: "Increased Iron Levels and Decreased Tissue Integrity in Hippocampus of Alzheimer's Disease Detected in vivo with Magnetic Resonance Imaging",
Erika P. Raven, Po H. Lu, Todd A. Tishler, Panthea Heydari and George Bartzokis. Journal of Alzheimer's Disease, Issue Volume 37, Number 1/2013, Pages 127-136, DOI: 10.3233/JAD-130209