It becomes more pronounced with age (as does everything else) but it is the little things that no one talks about.. eg. Clumsiness – one tends to trip over things or misjudge spaces; difficulty with speech – it seems like your brain cannot connect to your tongue (a bit scary). When I get off the plane I cannot speak Italian very well as the brain just will not switch over.
So I advice my clients to not make any important decisions in the first two days of arrival, be very careful crossing the road – look both ways twice before you step out particularly if you come from a country that drives on the other side of the road. Count your change if you go shopping to make sure you have not been short changed as your awareness is down. Keep all bags closed and under your arm if travelling on public transport and it is best to avoid driving if you can for the first two days until you feel normal again.