Optogenetic methods of Alzheimer's disease treatment

Optogenetic methods of Alzheimer's disease treatment

Alzheimer's disease, a neurodegenerative disease, occurs when toxic protein complexes from beta-amyloid accumulate in neurocytes.

A specific sign of Alzheimer's disease is a violation in the gamma-rhythms, necessary for memory, attention, perception. But the correct gamma-rhythms can be generated artificially. Optogenetic methods allow to turn on and off groups of neurons with the help of light pulses.

Cells of the memory center in the hippocampus can be stimulated at a frequency of 40 Hz, which reduces the level of beta-amyloid by 40-50%. Although gamma-rhythms vary from 25 to 80 Hz, stimulation of interneurons at other frequencies gives zero effects. And cells, other than interneurons, do not synchronize with the gamma activity of surrounding neurocytes.

However, optogenetic metod works only on genetically modified cells and when the optofiber is implanted into the brain. Quite an invasive method of treatment, so there was an alternative founded - you can use light pulses with the same effect. Flickering with a frequency of 40 Hz LEDs also cause gamma-rhythms, as a result of which the amount of beta-amyloid in the visual cortex reduces by half - although the level of dangerous protein rises back within a day.

Normally, the microglia of the brain cleans itself from dangerous molecules, but in Alzheimer's syndrome these cells themselves synthesize inflammatory signals. "Light therapy" normalizes the work of microglia.

Cross-examination at the Rensselaer Polytechnic Institute revealed a regression of sleep disorders and behavioral disorders after the use of adapted lighting. As a control, the Sleep Quality Index was used. The following results of application of combined lighting are those:

• active medical fluorescent lamp: 10.4 ± 0.4 base level vs.6.4 ± 0.5 after 4 weeks
• inactive medical fluorescent lamp: 9.7 ± 0.5 base level vs.8.0 ± 0.4 after 4 weeks

Researchers also published similar short-term improvements in patient agitational levels (measured by the Cohen-Mansfield Index of Agitation) at the International Conference of the Alzheimer's Association

• active fluorescent lamp (at the excitation): 43.6 ± 2.5 base level vs.37.5 ± 1.9 after 4 weeks
• Inactive fluorescent lamp (at the excitation): 41.5 ± 1.8 base level vs. 40.4 ± 1.9 after 4 weeks

and mood (measured by the Cornell scale for depression in dementia)

• active fluorescent lamp: 10,9 ± 1,1 base level vs.7,3 ± 0,7 after 4 weeks
• inactive fluorescent lamp: 10.6 ± 0.9 base level vs.9.1 ± 0.9 after 4 weeks

Light is the main synchronizer of circadian rhythms. Bright light, emitting more than the blue spectrum, can help improve circadian rhythms. Thanks to the new LED technology, it is much easier to control the intensity of light and color.