Ordinarily, naturalization applicants must be able to demonstrate knowledge and understanding of the United States history and the form and principles of the U.S. government (civics). If a disability prevents you from meeting this requirement, you can request an exemption from the civic test, by filing a Medical Certification for Disability Exceptions (USCIS Form N-648), signed by a physician, certifying your particular disability.
Applicants over 65 years of age, who have been a U.S. permanent resident for 20 years, may select the language in which they wish to take the civics test. In addition, they only need to study 20 of the 100 civics questions. Compare Civics Questions for the 65/20 Exemption with Civics (History and Government) Questions for the Naturalization Test.
Preparing for Citizenship Civics Test
Applying for Citizenship
Citizenship after Marriage to U.S. Citizen