Shift leader has dementia

We have a shift leader who sadly has dementia and is always forgetting things, he’s a old man and still works and manages the store, we have a group of colleagues who outright take the piss with him

We work the evening shift so altogether there’s the 4 of us including the security and we’re all entitled to a 30 min break what colleagues do is take their 30 min break but a few hours later ask the shift leader they want to go on break cos they haven’t taken it yet so they take another 30 min break despite their shift only being 7 hours even the security guard who takes an hour break tells the shift leader he still has half hour break left, they all take advantage of his dementia i find it so frustrating and upsetting how can someone take advantage of another persons illness???

Idk what to do whether to report it to the store manager or the protector line, any advice asap would be appreciated