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

The purpose of this research is to study the effects of Transcranial Direct Current Stimulation (tDCS) on clinical pain, mobility disability, and pain sensitivity to gain a better understanding of the factors that cause pain and disability in people with knee osteoarthritis (OA). In particular, people from different ethnic and racial groups may experience OA pain differently which is why the focus will be on older Asian Americans and non-Hispanic whites. It is important to find a reason for such difference so that a better treatment can be found for all OA patients. In addition, the research study will examine if there is any ethnic differences in pain and mobility disability. The investigator hypothesize that Asian Americans will report greater pain and mobility disability than non-Hispanic whites, and that active tDCS will result in improvement in pain and disability compared to sham tDCS.

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.

Eligibility Criteria:
Inclusion Criteria:

* they have self-reported unilateral or bilateral knee OA pain according to American College of Rheumatology criteria
* they can understand, speak and read English
* they are able to walk for 6-minutes
* they are willing to be randomized to either the intervention or control group
* they are available for five consecutive daily sessions and for a follow-up phone interview each week for three weeks post-stimulation sessions
* they have no plan to change medication regimens for pain throughout the trial
* they are willing and able to provide written informed consent

Exclusion Criteria:

* knee replacement or non-arthroscopic surgery to the affected knee
* serious medical illness, such as uncontrolled hypertension (i.e., Systolic Blood Pressure/Diastolic Blood Pressure of ≥ 150/95), congestive heart failure, pacemaker, or history of acute myocardial infarction
* peripheral neuropathy
* systemic rheumatic disorders, including rheumatoid arthritis, systemic lupus erythematosus, and fibromyalgia
* alcohol/substance abuse
* cognitive impairment (i.e., Mini-Mental Status Exam score ≤ 23)
* history of brain surgery, tumor, seizure, stroke, or intracranial metal implantation
* pregnancy or lactation for females
* hospitalization within the preceding year due to psychiatric illness