Massachusetts General Hospital said Thursday that a data breach in its neurology department has exposed the private information of nearly 10,000 people.

“An unauthorized third party’’ accessed data in two computer programs used by researchers in the department of neurology, Mass. General said.

The breach exposed data about participants in certain research programs, including their names, dates of birth, medical record numbers, and medical histories. Social Security numbers and financial information were not disclosed, according to the hospital.