i gave my dad some tests for demensure that someone advised on another site

Someone before advised me to give Dad some simple tests so I did. I gave him the clock test as someone advised on here. The hospital said they thought he may have demensure but as he lacked in vit B12 he had injections for this now, but his memory is still poor. I got him to draw the clock and at first he wrote on it 12 at top 6 bottom, 9 on the side where it should be, and then he started writing where the 3pm should be, 112 then after 113 then 14, instead of writing 3pm 4pm 5pm etc, I got him to do the clock again and he asked me 3 times how I wanted it written. Did I want the 24hr clock I said No, just 1 to 12, and it took him like 10 minutes to do it really. He wrote out most of it and then wrote an 8 where the 9 should be and crossed it out and wrote 9. Anyone had any experience of this or maybe knows more?