When the researchers examined brains of patients who died from Alzheimer's, they discovered the brains all contained droplets of fat. Could there be a connection?
"Our experiments suggest that these abnormal fat deposits could be a trigger for the disease", said Karl Fernandes, a researcher at the hospital and a professor at the University of Montreal.
The study started out as a way to solve the mystery of why the brain's stem cells don't repair brain damage in people with Alzheimer's like they would with other brain injuries and diseases. Doctoral student Laura Hamilton, who was conducting the research, said she was astonished to find fat droplets near the stem cells on the inner surface of the brain in mice predisposed to develop the disease.
"We realized that Dr. Alois Alzheimer himself had noted the presence of lipid accumulations in patients' brains after their death when he first described the disease in 1906,” she said. “But this observation was dismissed and largely forgotten due to the complexity of lipid biochemistry."
Further research revealed the fat deposits on the brains of nine Alzheimer's victims were triglycerides enriched with specific fatty acids, which can also be found in most animal fats and vegetable oils.
"We discovered that these fatty acids are produced by the brain, that they build up slowly with normal aging, but that the process is accelerated significantly in the presence of genes that predispose to Alzheimer's disease," said Fernandes.
In animal experiments, the researchers found that the fatty acids occur very early in life, correspnding in human years to the early twenties.
Cause or consequence?
Therefore, we think that the build-up of fatty acids is not a consequence but rather a cause or accelerator of the disease," Fernandes said.
If it turns out that these fat deposits are a significant contributor to Alzheimer's, the researchers say it would be a huge breakthrough. That's because there are existing drugs that inhibit the enzyme that produces these fatty acids.
The research team concludes these molecules, which are currently being tested for metabolic diseases such as obesity, could be effective in treating Alzheimer's disease.
"We succeeded in preventing these fatty acids from building up in the brains of mice predisposed to the disease. The impact of this treatment on all the aspects of the disease is not yet known, but it significantly increased stem cell activity," Fernandes said. "This is very promising because stem cells play an important role in learning, memory and regeneration."
The researchers say their discovery also supports the argument that Alzheimer's disease is a metabolic brain disease, almost like obesity or diabetes. They say it could lead to an entirely new approach to treatment.