State psychologist Maria Teresa Napoli, testifying Monday in Milan in Berlusconi's defense, said Karima "Ruby" el-Mahroug, a teen prostitute and runaway, "escaped into an imaginary world to flee from reality as a defense mechanism," ANSA reported.
Berlusconi is on trial for allegedly having sex with el-Mahroug when she was 17 and underage, and allegedly abused his power on her behalf. He has denied the charges. Prostitution is legal in Italy.
On the stand, Napoli said lies attributed to el-Mahroug "were due in part to her conflicted personality and form of autism."
Napoli, who said she conducted about 20 interviews with el-Mahroug, described the teen as a "smart and sharp girl" who was "torn between a modern culture and that of her father."
Berlusconi was convicted in October of tax evasion and sentenced to three years in prison but that conviction has been appeal.