Transcranial Direct Current Stimulation in Older Persons With Knee Pain (Knee Pain and tDCS): Randomized Pilot Study

If you participate in the study, the following will happen: Randomized into one of two groups. Which will either receive the full length session of brain stimulation or a much shorter session of brain stimulation. The shorter version of stimulation looks like and is performed in the same way as the longer electrical stimulation session, but stimulation is stopped before it can have much of an effect on the brain. You will not know which group you have been assigned to while participating in the research, but you may find out at the completion of the research study. X-Rays will be done on both knees while standing up. Questionnaires about arthritis pain you are having, your thoughts and feelings about it, and any stress that you may have experienced. Walking Test will be performed on a flat surface for 6 minutes at a fast pace without help from an assistive device (cane or walker) or another person. Assessment of Physical Performance requires walking at short distance (about 13 feet), stand up from a chair 5 times without using your arms, and stand in 3 different positions while keeping your balance. Assessment of Sensitivity to Heat. Heat pain sensitivity will be tested using a commercially available thermal sensory testing machine (Medoc, Inc.) used widely in clinical settings. This machine has a small (about 1 inch by 1 inch) square piece that is used to apply heat to the skin. Heat will be applied to the knees and arms. The amount of heat is controlled by a computer. One or more of the following types of heat stimuli will be delivered: 1) a slowly increasing heat that can be stopped by pressing a button when it becomes warm, painful, or intolerable; 2) a series of 5-10 heat pulses that are brief (less than 2 seconds in duration), and rate how painful each heat pulse feels; and 3) a few longer heat pulses (15-30 seconds) at different temperatures to rate how painful each heat pulse feels. The procedures can be stop at any time. Assessment of Sensitivity to Pressure will be done using a handheld device with a small rubber tip to apply pressure to the knee, thigh, and shoulder. Assessment of Sensitivity to Mechanical Stimulation will be done using a handheld probe that has a small nylon tip to tap both the knee and hand. Blood Draw: Blood will be taken at the baseline visit and at the last visit. Brain Stimulation: The stimulation technique called transcranial direct current stimulation (tDCS) and it involves placing two sponge-like electrodes on your head and delivering a very weak electrical current to your scalp, which is generated by a 9 volt battery. In addition, weekly phone calls will be done for the next 3 weeks.