It's hard to say but as long as the time traveler lands in a time of rationality, science, and logic then they can fare a lot better than otherwise.
They face problems such as
* Solitude and isolation - the inability to relate to others for a while until they can develop the language which has most certainly changed in large time scales and they can comprehend and grasp the reality around them.
* Discontinuity - See <PERSON> Why and how normal people go mad.
When students were led to wrongly believe that the source of their anxiety was physical, they began to show signs of hypochondria or somatoform disorders. And attributing such discontinuities to social causes created paranoid symptoms.
It's quite possible that sudden changes in routine and environment can trigger similar phenomena. In this case, the issue would be how they interact with people in the future. The anxiety they might have from simply traveling to the future might be exacerbated by their inability to understand social cues and norms. You could imagine a bleak future where their struggles are taken as a form of dimness or disorder by the main population, until the issue snowballs and they can never fulfill their needs for roots, love, compassion, esteem, or self-actualization.
* Grief - See <PERSON> great answer on this - The person's family might be left behind. Their friends. 494
Their peers. Everything they knew is going on in their own timeline without their help, possibly suffering or dying without their provider (if they were the provider.)
* Lack of esteem - How can they get a job or feel a sense of contribution and value if they're so far behind technology or the current job market?
These are all real and valid issues - but they're not the end all be all of their situation.
See, the future citizens aren't necessarily stupid. They know that this person needs help. They know that mental disorders are real. They know that there are disadvantaged people in their midst, from the mentally disabled to the mute to the illiterate.
It'd be a bit unfair to not take the rest of the population's feelings into account. If they're accommodating, it's easy to see how they might push the person's development in a positive direction. This depends heavily on when this is, but if we (2016-farers) went to 2500, we could easily imagine that their psychological therapies, medical science, and neurological understanding (and maybe social programs, depending on culture) could help us adapt.
Not only are the problems not necessarily insurmountable, they could be less negative than we imagine, and the people more welcoming and accommodating than we imagine, helping time travelers become well adjusted members of society. 693