Under the federal Social Security Disability Act, "disability" means the "inability to engage in any substantial gainful activity by reason of any medically determinable, by a physician, physical or mental impairment which can be expected to last for a continuous period of not less than 12 months or result in death." A medical disability is an impairment caused by a physical condition or a mental condition which results in the inability to perform gainful employment to provide financial support for the claimant and/or his family members.