  We present the results from the study of the resolved distribution of cold
molecular gas around eight young (<10^6 yr), peaked-spectrum radio galaxies.
This has allowed us to trace the interplay between the radio jets and the
surrounding medium. For three of these sources we present new CO(1-0)
observations, obtained with NOEMA. In two targets, we also detected CN lines,
both in emission and absorption. Combining the new observations with already
published data, we discuss the main results obtained. Although we found that a
large fraction of the cold molecular gas is distributed in disc-like rotating
structures, in most of the sources high turbulence and deviations from purely
quiescent gas (including outflows) were observed in the region co-spatial with
the radio continuum emission. This suggests the presence of an interaction
between radio plasma and cold molecular gas. We found that newly born and young
radio jets, even those with low power i.e., P_jet<10^45 erg/s), can drive
massive outflows of cold, molecular gas. The outflows are, however, limited to
the sub-kpc regions and likely short lived. On larger scales (a few kpc), we
observed cases where the molecular gas appears to avoid the radio lobes and,
instead, wraps around them. The results suggest the presence of an evolutionary
sequence, consistent with simulations, where the type of impact of the radio
plasma changes as the jet expands, going from a direct jet-cloud interaction on
sub-kpc scales to a gentler pushing aside of the gas, increasing its turbulence
and likely limiting its cooling. This effect can be mediated by the cocoon of
shocked gas inflated by the jet-cloud interactions. Building larger samples of
young and evolved radio sources for observation at a similar depth and spatial
resolution to test this scenario is now needed and may be possible thanks to
more data becoming available in the growing public archives.
