What is the effect of improper testimony in the guilt phase of the trial of a defendant in a sexual assault case?

We agree with the trial court that although the evidence regarding defendant's sanity was improper in the guilt phase of the trial, its admission did not irreparably damage defendant's chance of receiving a fair trial. Defendant's sanity was not an issue in the guilt phase and was irrelevant to the defense theories of heat of passion and the effects of methamphetamine on intent. After the improper testimony, the trial court immediately admonished the jury to disregard it, and we presume the jurors followed the instruction. (See, e.g., People v. Mickey (1991) 54 Cal.3d 612, 689, fn. 17.) Under these circumstances, the court did not abuse its discretion in denying the motion for a mistrial.