Very little spillover. From what I've read, it didn't even impact his ability to memorize a string of random alphabetic characters. That said, people have done a lot with mnemonic techniques to accomplish amusing tasks like memorizing the order of 27 decks of cards in an hour, and some techniques there can be trained for a somewhat wider range of tasks.
Unlimited Memory: How to Use Advanced Learning Strategies to Learn Faster, Remember More and be More Productive is free with an Amazon prime subscription for those that are interested in the "learning how to learn." resource.
My college days started in the early 90's, so it's been a long time, and I'm not a biochemist, but I have a tip to share with you, and anyone else who is about to embark on the college journey: Learn memory techniques, if you haven't already. There are various sources on the subject. I like learning by reading. One easy book on the subject is Unlimited Memory: How to Use Advanced Learning Strategies to Learn Faster, Remember More and be More Productive
One other thing that may interest you, being a good visualiser, is the potential for developing mnemonic techniques.
If you have an amazon account, you can read the first few chapters of the following book for free ("download sample"), the exercise described in chapter five "use you car to remember" - about 3 pages of description - should give you a flavour of what is possible.
You can use this to make a lot of use of visualisation skills in an academic setting, mostly through an increased ability to memorise and recall lists.
Hey man, I can say with honesty after working for a straight year with very little sleep, working in a very similar situation at least in terms of depression and being overworked. I didn't realize quite how depressed I was until I got on antidepressants. Night and Day man.
I don't know the exact details of your situation but I'd say the #1 contributing factor in what made me feel like what you are describing is the burnt-out mood from being over-worked and no sleep. I had to hit rock bottom and move back in with my mother with whom I have a very rocky past, but I was able to take some time off from 1 of my jobs and just having that time to myself is such a breath of fresh air.
I was able to save some money, set up some medical appointments I'd been putting off for several years and now in the coarse of about 3 months have managed to get a foothold on my life in a few ways, the biggest thing of which has actually been memory-improvement which stemmed from the problems associated with little to no sleep. This one thing in particular has completely changed my outlook on life, especially in terms of learning, because after you get the methods down, it's just a matter of how creative you can be with how you use them. My personal goal is 1 book a week, taking notes and then memorizing the notes, dude let me tell you, I don't know what the fuck school is doing right now because this should be taught everywhere.
A good start is this book right here: http://www.amazon.com/Unlimited-Memory-Advanced-Strategies-Productive-ebook/dp/B00I3QS1XQ/ref=sr_1_4?s=digital-text&ie=UTF8&qid=1446341306&sr=1-4&keywords=memory+improvement
The best tool I've found for memorising large numbers / number sequences is the Major System. I learned about it in the book Unlimited Memory (which is well worth a read) by Kevin Horsley.
I suggest looking into the techniques that memorization champions utilize. They focus less on repetition and more on how they digest information. You can check out some books like Unlimited Memory or Moonwalking with Einstein.
https://www.amazon.com/Unlimited-Memory-Advanced-Strategies-Productive-ebook/dp/B00I3QS1XQ
I just got this book. Just gonna stick with one book.