16 year old needing advice for memory loss

Have you seen your doctor for a general check-up and routine blood tests? You're in the right age-group for a viral infection called infectious mononucleosis (more commonly known as glandular fever or "kissing disease"). This famously causes brain fog and general malaise in some young people. You might also be anaemic, which could cause fatigue. Get yourself thoroughly checked out.

Apart from that, I stand by what I said last time - that this is probably down to stress. People your age don't suffer from dementia. However, some of us are chronically absent-minded throughout life, starting in childhood. That was certainly true for me but it hasn't stopped me living a long, healthy life!

And of course, you need to get enough of the right kind of sleep. That means avoiding all use of computers, tablets, iPhones etc. in the last hour or so before going to bed. It's been discovered that the bluish light emitted by these gadgets (especially when used in a darkened room, e.g. when in bed at night) affects the body's production of hormones that bring on health sleep.

Get yourself checked out by a doctor, then try not to worry about it. Many people of your age go through phases like this. You'll eventually grow out of it.