HOW TO DETERMINE WHETHER A PERSON HAS A DISABILITY UNDER THE AMERICANS WITH DISABILITIES ACT AMENDMENTS ACT (ADAAA) - from the Job Accommodation Network
https://askjan.org/publications/consultants-corner/vol05iss04.cfm
The definition of disability is an impairment that substantially limits a major life activity. So when determining whether an employee has a disability, you need to know:
Does the employee have an impairment? If yes,
Does the impairment affect a major life activity? If yes,
Does the impairment substantially limit the major life activity? Keep in mind:
If an impairment is on the EEOC's list of conditions that are virtually always disabilities, get the diagnosis and move on to making the accommodation. If not on the list:
Consider how limited the employee would be without any mitigating measures
Consider how limited the employee is when the impairment is active.
If needed, consider the condition, manner, or duration in which an employee performs a major life activity.