The New York Times has a good article Studies show more students cheating, with high achievers no exception which is worth reading.
Here are a few practical suggestions to those of us involved in teaching.
1. Don't live in denial. It does happen.
2. Make sure at several stages in a course (e.g., the introduction, before specific assessment is due) tell/remind/exhort students about cheating. Try and be specific about what it is and isn't.
3. Don't assume that just because you said it once in class or wrote it in the course profile that students heard, understood, or internalised it.
4. When it does happens, make sure you do discipline students, in accordance with course and institutional policies. Private words and "slaps on the wrist" are ineffective. It is very important that student records reflect repeat offences.
Unfortunately, all of the above is a hassle and just increases our workload. But, if we don't act nothing is going to change.
I welcome other suggestions.