Treatment with ultrasound could improve memory deficits in Alzheimer’s disease, even if it doesn’t break down amyloid plaque, according to a new study. The effect also seems to depend on the frequency of the ultrasound.
Researchers at the University of Queensland have shown in mice that repeated ultrasound treatment can improve memory deficits in Alzheimer’s disease without reducing beta-amyloid burden. The corresponding study results are published in the specialist magazine “Molecular Psychiatry”.
Role of beta-amyloid plaques
Although the underlying mechanisms in Alzheimer’s have not yet been fully clarified, the deposits of beta-amyloid plaques are considered to be of great importance.
“Amyloid plaques are clumps of proteins that build up in the brain and can block communication between brain cells, leading to memory loss and other symptoms of Alzheimer’s disease,” explains Dr. Gerhard Leinenga from the Queensland Brain Institute (QBI).
So far, the assumption has been that treatment must address the underlying amyloid plaque pathology for cognitive improvements.
“Previous studies have therefore focused on opening the blood-brain barrier with microbubbles that activate the type of cell in the brain called microglia that removes amyloid plaque,” said Dr. Linenga.
Ultrasound treatment works
In the new study, the researchers were now able to show on mice that ultrasound treatment leads to improvements in Alzheimer’s disease even without opening the blood-brain barrier and without reducing amyloid plaque.
Further studies of the mice’s brains (including using functional magnetic resonance imaging) showed that the ultrasound treatment caused long-lasting functional changes that correlated with improved memory, the experts report.
Interestingly, the treatment was more effective at a higher frequency (1 MHz) than at a frequency within the range currently being studied in Alzheimer’s clinical trials (286 kHz), the research team continued.
Higher frequency more effective
“We tested two types of ultrasound waves emitted at two different frequencies, (…) and found that the higher frequency gave better results compared to frequencies currently being studied in clinical trials for Alzheimer’s patients,” emphasizes Professor Jürgen Götz from QBI.
The treatment had direct effects on neurons, increasing plasticity and improving brain networks, adds Dr. Gerhard Leinenga. The researchers assume that ultrasound increases the brain’s resistance to plaques, even if they are not removed.
“By understanding the mechanisms underlying ultrasound therapy, we can tailor treatment strategies to maximize cognitive improvements in those affected,” said Dr. Linenga. (fp)
