How Your Brain Ages Infographic

Research suggests that accumulation of the plaque forming amyloid-beta protein is crucial for development of Alzheimer’s. And not only the quantity of amyloid-beta peptides, but also the quality is critical for initiation of Alzheimer’s.

An imbalance triggers Alzheimer’s; there is a decrease in healthy amyloid-beta 40 levels in comparison to 42 levels.

Two key features of the circuits in the brain which impact this critical balance have been uncovered. Electrical pulse patterns in the form of high-frequency bursts, known as spikes, and the synapses’ filtering properties are critical to the ratio of amyloid-beta 40/42 regulation. The ratio of amyloid-beta 40/42 is improved by synapses transferring information in spike bursts.

This presents a significant advance in understanding that circuits in the brain regulate amyloid-beta protein composition, showing that Alzheimer’s is also driven by physiological mechanisms and just by genetic mutations.

The brain’s high-frequency bursts are crucial for memory encoding, information processing and brain plasticity. To examine the association between spike patterns and amyloid-beta 40/42 ratio regulation, electrical pulses were applied to the hippocampus, the area of the brain involved in memory and learning.

When the rate of low frequency single pulses in rat hippocampal slices was increased, both amyloid-beta 42 levels and 40 levels grew, with the 40/42 ratio staying the same. When the identical amount of pulses was however sent out in high-frequency bursts, an increased amyloid-beta 40 production was seen. The spiking pattern and the kind of amyloid-beta produced association could revolve around a protein known as presenilin. The researchers theorize that structural changes in the presenilin could be triggered by the temporal pattern of spike changes in the hippocampus, resulting in early impairments of memory in individuals having sporadic Alzheimer’s.

The synapse properties can be modified by different kinds of experiences and environmental changes – including emotional and sensory experience – and change the brain’s spiking patterns. Prior studies have indicated that a stimulant-rich environment, such as crossword puzzles that stimulate the brain, could contribute to the prevention of Alzheimer’s.

References: DOI: 10.1038/nn.3376