Show, don't tell.
In most fields hiring managers don't care about "unusual talents". They want to know why you're the person who can get the job done. The goal of your resume is to highlight relevant and useful experience that makes you a good candidate for the position. The cover letter does most of the same but offers you the opportunity to add a human touch and sell your profile. It's a marketing document but one that should be grounded in reality, which is to say your work experience. It doesn't matter if the talent is unusual, all that matters is if it adds value to your resume.
Anyone can claim an excellent memory or good pattern recognition skills. You have to back that claim up. The way you do that in an application is by referring to specific accomplishments, milestones or praise from your work experience. Every mention of an experience or skill in your cover letter should also be linked to your work experience. As an example, if you're trying to sell your excellent memory as a skill, say something along the lines of: "quickly developed working knowledge of multiple new programming languages to achieve [X]" where X is a significant project or accomplishment.
Again, the point is to highlight skills that you'll be able to use in the position that you're applying for. Find ways in which you used them in the past that you can also benefit from in the future. As for interviews: anything that makes you a better candidate should have already been contained in your resume or cover letter. Don't ever "save" something for the interview as that will likely have an undesired negative effect as I'm going to wonder why you didn't include it in your application.
As a general note, do not ever list a medical condition on a resume, cover letter or anything else. They simply do not belong there and including one is a great way of having your candidacy immediately rejected without so much as a phone screen. Hiring managers and HR are wary of anyone who seems ignorant of workplace norms and are especially reluctant to start a hiring process for someone who disclosed a medical condition (or religion, pregnancy, ...) for fear of appearing to discriminate if they end up rejecting the candidate.