  The presence of a stellar companion closer than ~100 AU is likely to affect
planet formation and evolution. Yet, the precise effects and their actual
impact on planet occurrence are still debated. To bring observational
constraints, we have conducted with VLT/NACO a systematic adaptive optics
survey for close stellar companions to 130 solar-type stars with and without
planets. In this paper we present observational and preliminary statistical
results from this survey. Observational results reveal about 20 true
companions, of which 4 are new companions to planet-host stars. As to
preliminary statistical results, they suggest that circumstellar giant planets
are less frequent in binaries closer than ~100 AU than around single stars, in
possible agreement with the theoretical studies that predict a negative impact
of stellar duplicity on giant planet formation in binaries closer than ~100 AU.
These statistical results will need confirmation, however, as they are severely
limited by small sample sizes.
