To be “totally” disabled, the individual must be substantially prevented by reason of a permanent
                  impairment from engaging in a useful occupation within his competence.
               
               The impairment must result in such a lack of ability to perform significant functions
                  as to substantially prevent performance of activities required by a useful occupation
                  for which the individual is qualified. The individual does not have to be completely
                  helpless. The fact that the individual is unable to carry out his last or usual occupation
                  does not in itself qualify him as totally disabled. The occupation must be one for
                  which he is qualified by age, training, education, work experience, or natural ability.
               
               Total disability does not involve consideration of how long the individual will be
                  unable to engage in a useful occupation. Even though the impairment meets the definition
                  of “permanent,” a finding of total disability is possible even though treatment or training might
                  later make possible the performance of a useful occupation.
               
               The determination of total disability will be made on the facts of each case. This
                  will require evaluation of the severity of the impairment, and of its effect on the
                  individual, and finally, consideration of the individual's abilities so that it can
                  be determined whether there remains a capacity to engage in a useful occupation. Thus,
                  with two individuals having the same impairment of a like degree of severity, one
                  may be totally disabled and the other not totally disabled because of variations in
                  social factors.
               
               Various borderline emotional and psychiatric conditions should be looked into with
                  increased individualization of the patient and with particular attention given to
                  how “totally” disabled the person is in light of his social situation, past and present, including
                  built-in obstacles to emotional recovery including evaluation of past successes and
                  failures as evidenced by school and work histories, strong or weak marital relationships,
                  etc. The degree of disability is very difficult to evaluate in this area so that each
                  case needs to be evaluated independently on its own merits.
               
               An impairment may be more limiting for an older person than for a younger person since,
                  in addition to its influence on the permanence of the impairment, the aging process
                  also affects psychological adaptability, general health, speed and efficiency. The
                  amount of training and education a person has is a factor in determining his adapt-ability
                  to other occupations when he is unable to continue his usual occupation. An individual
                  who all his life has done simple unskilled work may find it difficult to adjust to
                  a different occupation if he acquires a handicap that prevents him from carrying on
                  the work in which he is experienced. Experience in unskilled work only, especially
                  when paired with limited education, may indicate limited vocational adaptability.
                  On the other hand, a trained person with varied work experience very often is able
                  to make vocational adjustments.