concurring specially.
I agree that the trial court did not err in excluding testimony from Turtle’s expert witness regarding the symptoms of manic depression or bipolar disorder because there was no evidence that Turtle suffered from this mental illness. However, if the expert had diagnosed Turtle as manic depressive, then his testimony would be relevant and admissible. Turtle did not want to simply renounce his prior incriminating statements; he wanted to provide the jury with a credible explanation for the cause of his fabrications. Furthermore, the expert would not have testified that any particular statement was untruthful.
The focus on mental illness distinguishes this case from those in which the mere veracity of the defendant’s statements is at issue. We have previously recognized that expert testimony may be helpful to the jury even when it touches upon the question of a witness’s truth*446fulness.3 Therefore, when a mental illness impacts the defendant’s veracity and an expert witness is offered to describe that mental illness, the testimony should be admitted.
Decided September 13, 1999. Sharon L. Hopkins, for appellant. Daniel J. Porter, District Attorney, Thomas N. Davis, Assistant District Attorney, Thurbert E. Baker, Attorney General, Jeanne K. Strickland, Assistant Attorney General, for appellee.Barlow v. State, 270 Ga. 54, 55 (507 SE2d 416) (1998) (expert testimony regarding interview techniques for child molestation victim admissible even though it indirectly involves witness credibility).