I just don't think you can learn much by comparing Russia with western Europe and North America. There are too many radically different variables.
Source: https://lendedu.com/blog/millennials-instagram-narcissistic-...
See the chart comparing narcissism on various social platforms.... The 'Gram is waaay ahead.
Shallow "hey look at me posts" don't bother me as much as just a lot of generally, even if mildly, negative thoughts and observations.
Admittedly, I've long had a very strained and irritated relationship with my Twitter feed, even if I still enjoy the people I follow personally. I just get a much more negative feeling when using Twitter. Just could be me though.
To a lesser extent, I'd cast a skeptical glance on this kind of data any society with collectivist pressures until presented with a very high standard of evidence that the participants were convincingly guaranteed their responses were untraceably dissociated from their regular lives.
Besides that you seem to have no idea how society actually worked in Eastern Germany - trust to medical personel was actually pretty high and health care was good. STEM subjects were hard science and also medicine education was good. Not sure about psychiatry but western countries did lobotomy until the 80ies...
So I guess if they would have screened in the GDR for that, the data might be accurate enough - but you didn't bother to read the abstract.
Stasi worked different - they didn't bother with regular folks but were focussed on dissidents (wearing blue jeans and having long hair was often enough, through) and people in power positions or with connections outside of GDR were targeted.
Reprisal was not like in North Korea where you end up in the gulag (stuff like that happend, I just want to clarify not excuse them) - it was a much more nuanced system - you don't get the flat or job an stuff like this.
People planning for or announcing public discontent with system got often harsh treatment but everday folks could speak open as long as you didn't articulate discontent with the system - even that was allowed to a certain degree.