SUMMARY
The folding model analysis of the elastic a+a\alpha + \alpha scattering at the incident energies below the reaction threshold of 34.7 MeV (in the lab system) has been done using the well-tested density dependent versions of the M3Y interaction and realistic choices for the 4^4He density. Because the absorption is negligible at the energies below the reaction threshold, we were able to probe the a+a\alpha + \alpha optical potential at low energies quite unambiguously and found that the a + a overlap density used to construct the density dependence of the M3Y interaction is strongly distorted by the Pauli blocking. This result gives possible explanation of a long-standing inconsistency of the double-folding model in its study of the elastic a+a\alpha + \alpha and a\alpha-nucleus scattering at low energies using the same realistic density dependent M3Y interaction.