James Holmes appeared in court for the first time without his wild orangish-red hair. He had short brown hair and appeared more animated during the hearing than in the past.
Defense attorneys say Holmes is mentally ill and that the notebook, sent to Dr. Lynne Fenton, shouldn't be released because of doctor-patient privilege.
During the hearing, Holmes smiled and glanced around the courtroom, looking at his lawyers and reporters. He appeared to be moving his mouth but not actually talking.
The district attorney said even if the judge allowed prosecutors to look at the contents of James Holmes' notebook, the ruling would likely have been appealed, and the D.A. doesn't want to delay the trial.
Also, if Holmes pursues an insanity defense, the suspect would have to waive privilege, and prosecutors would gain access to the notebook.
Holmes is accused of killing 12 people and wounding 58 others at a movie theater near Denver on July 20. He has been charged with 142 counts, including murder and attempted murder. Judge Sylvester on Thursday approved prosecutors' request to add 10 additional attempted murder charges and amend 17 others.
The Associated Press contributed to this report.