^^ Yes, this; and also that sometimes you might not even notice some things that would be plainly obvious to another person.
If that still all sounds a bit vague, it's probably because "cognitive deficits" covers a huge range of different traits and impairments. If you can, I would ask your doctor to explain in more detail, as without knowing exactly what deficits he means, it's hard to know how it applies to you personally.
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When you are fighting an invisible monster, first throw a bucket of paint over it.