A method and device for treating a condition aggravated by the presence of amyloid fibrils is disclosed. The method includes applying a plurality of ultra-short pulses to target tissue comprising amyloid fibrils. The plurality of ultra-short pulses produce an electric field in the target tissue sufficient to change a molecular structure of the amyloid fibrils without causing the death, destruction, or serious injury of healthy cells surrounding the target tissue. For example, the plurality of ultra-short pulses can be sufficient to change the molecular structure of amyloid fibrils without causing apoptosis or necrosis of surrounding cells. The ultra-short pulses can be applied using an electrode device or a wideband antenna. The ultra-short pulses can have a duration ranging from 1 ps to 10 ns, an amplitude ranging from 100 V to 1 MV, and can apply an electrical field to the target tissue ranging from 1 kV/cm to 1 MV/cm.