Non-invasive magnetic or electrical nerve stimulation to treat or prevent dementia
Devices, systems and methods are disclosed for treating or preventing dementia, such as Alzheimer's disease. The methods comprise transmitting impulses of energy non-invasively to selected nerve fibers, particularly those in a vagus nerve, that modulate the activity of a patient's locus ceruleus. The transmitted energy impulses, comprising magnetic and/or electrical energy, stimulate the selected nerve fibers to cause the locus ceruleus to release norepinephrine into regions of the brain that contain beta-amyloids. The norepinephrine counteracts neuroinflammation that would damage neurons in those regions and the locus ceruleus, thereby arresting or slowing the progression of the disease in the patient.
1. A method of treating or preventing dementia in a patient, the method comprising:
positioning one or more electrodes in contact with an outer skin surface of a neck of the patient, wherein a housing includes an exterior portion and an interior portion, wherein the exterior portion includes the one or more electrodes, wherein the interior portion contains a power source coupled to the one or more electrodes;
generating an electric current with the power source; and
transmitting, during the positioning, the electric current non-invasively and transcutaneously from the power source via the one or more electrodes through the outer skin surface of the neck to a vagus nerve in the patient, wherein the electric current comprises a single signal comprising bursts of pulses with each of the pulses having a duration from about 20 microseconds to about 1000 microseconds and each of the bursts followed by a silent intra-burst period such that each of the bursts has a frequency from about 15 Hz to about 50 Hz, and wherein the electric current is sufficient to modify dementia within the patient.
2. The method of claim 1 , wherein the housing comprises a conducting medium, wherein the transmitting is through the conducting medium.
3. The method of claim 1 , further comprising:
generating an electric field at or near the housing; and
shaping the electric field such that the electric field is sufficient to modulate a nerve fiber at a target region; and wherein the electric field is not sufficient to substantially modulate a nerve or muscle between the skin surface and the target region.
4. The method of claim 3 wherein the electric field at the vagus nerve is about 10 to about 600 V/m.
5. The method of claim 4 wherein the electric field is less than 100 V/m.
6. The method of claim 3 wherein the vagus nerve is at least approximately 0.5-2 cm below an outer skin-surface of the patient.
7. The method of claim 1 wherein each of the bursts contains from about 1 pulse to about 20 pulses.
8. The method of claim 1 wherein the pulses are full sinusoidal waves.
9. The method of claim 1 wherein the duration of a pulse within a burst is about 200 microseconds, wherein a number of pulses per burst is from about 4 to about 6, and wherein a number of bursts per second is from about 20 to about 30.
10. The method of claim 1 wherein afferent nerve fibers of the vagus nerve are stimulated.
11. The method of claim 1 wherein the electric current generates an electric field at the vagus nerve above a threshold for generating action potentials within A and B fibers of the vagus nerve and below a threshold for generating action potentials within C fibers of the vagus nerve.
12. The method of claim 1 wherein the electric current generates an electric field at the vagus nerve above a threshold for generating action potentials within fibers of the vagus nerve responsible for activating neural pathways causing release of inhibitory neurotransmitters within a brain of the patient.
13. The method of claim 12 wherein the inhibitory neurotransmitters comprise norepinephrine.
14. The method of claim 13 wherein the norepinephrine is released into a resting state neural network of the patient.
15. The method of claim 14 wherein the resting state network is a default mode network or a ventral attention network.
16. The method of claim 13 wherein the norepinephrine counteracts neuroinflammation in or around a locus ceruleus of the patient.