Aspect Medical Systems Announces Interim Results of BRITE Major Depression Study at Annual Meeting of the American Psychiatric Association.

-Multicenter trial underway to evaluate Aspect's brain assessment technology as a one week indicator of response to antidepressant treatment-

NORWOOD, Mass. -- Interim study results from the BRITE (Biomarkers for Rapid Identification of Treatment Effectiveness) trial in major depression will be presented today at the annual meeting of the American Psychiatric Association taking place in San Diego, CA. Interim findings from BRITE suggest that Aspect Medical System's EEG-based research technology is a significant predictor of patient response to treatment of depression with a selective serotonin reuptake inhibitor (SSRI) after one week of treatment. Further, the study results suggest that the technology may help expedite the process of identifying effective antidepressant drug therapy.

"There are more than 20 antidepressants available on the market today, and all of them are effective for relieving the symptoms of depression. The problem is that the majority of patients will not respond adequately to the first antidepressant treatment they are prescribed," said Andrew Leuchter, M.D., Professor of Psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA, principal investigator for the trial, and chair of Aspect's Neuroscience Advisory Board. "Given that the current trial and error approach to finding an efficacious regimen typically takes many weeks, having the ability to determine treatment response more quickly would be an important clinical advance. The interim findings from BRITE are encouraging in that they are consistent with results from prior studies suggesting that there is an early brain signal of response to antidepressant treatment."

Interim BRITE study results indicate that Aspect's Antidepressant Treatment Response (ATR) index achieved statistical significance in predicting seven week clinical response as measured by the standard Hamilton Depression Rating Scale after just one week on treatment with an SSRI. In addition, a retrospective analysis of BRITE trial subjects demonstrated that patients who received treatment in accordance with the ATR index were significantly more likely to respond to treatment than the other patients in the trial. "These findings suggest that the ATR index may also help us identify the right antidepressant treatment to provide relief for patients," said Dr. Leuchter.

In the United States alone, an estimated 15 million people experience a depressive episode each year, and nearly 17 percent of adults will experience major depression in their lifetime. The majority of patients being treated for major depression are prescribed a SSRI. While treatment with antidepressants will eventually lead to remission in the majority of treated patients, many will require a second, third or fourth treatment before experiencing relief.

"These interim BRITE trial results are encouraging and support our belief that we can develop a practical, easy-to-use brain assessment device to help clinicians optimize care for patients suffering from depression," said Nassib Chamoun, president and CEO of Aspect Medical Systems. "We look forward to evaluating the final BRITE study data later this year."

Aspect is conducting the BRITE trial in collaboration with leading depression researchers at ten prestigious facilities across the United States. Enrollment for the 375+ subject trial was completed in March 2007 and an analysis of the full study results is planned for the second half of the year. More information about the BRITE trial is available at www.brite-md.com.

Aspect Conference call

Aspect Medical Systems, Inc. will host a conference call and live Webcast at 5:00 p.m. Eastern time for all interested parties, including financial analysts, portfolio managers, individual investors and members of the press. To participate in the call, please dial 1-866-406-5408 (domestic), 1-973-582-2770 (international), or access the Webcast at www.aspectmedical.com on the Investor page, or at www.earnings.com. Supplemental information about the BRITE trial will also be available to guide the conference call and will be posted on the investor page of the Aspect Medical Systems Web site at http://investor.aspectmedical.com. Telephone replays will be available by dialing 1-877-519-4471 (domestic), or 1-973-341-3080 (international), access code 8805001. The Webcast replay will be available from May 21, 2007 at 8:00 p.m. Eastern time to May 28, 2007 at 11:59 p.m. Eastern time.

About Aspect Medical Systems, Inc.

Aspect Medical Systems, Inc. (NASDAQ: ASPM) is a global market leader in brain monitoring technology. To date, the Company's Bispectral Index (BIS) technology has been used to assess approximately 20 million patients and has been the subject of more than 2,800 published articles and abstracts. BIS technology is installed in approximately 75 percent of hospitals listed in the July 2006 U.S. News and World Report ranking of America's Best Hospitals and in approximately 55 percent of all domestic operating rooms. In the last twelve months BIS technology was used in approximately 16 percent of all U.S. surgical procedures requiring general anesthesia or deep sedation. BIS technology is available in more than 160 countries. Aspect Medical Systems has OEM agreements with eight leading manufacturers of patient monitoring systems. The company is also investigating how other methods of analyzing brain waves may aid in the diagnosis and management of neurological diseases, including depression and Alzheimer's disease. For more information, visit Aspect's Web site at http://www.aspectmedical.com.

Safe Harbor Statement

Certain statements in this release are forward-looking and may involve risks and uncertainties, including statements with respect to the potential ability of the Company's brain assessment technology to predict the effectiveness of antidepressant medications and expedite the process of identifying effective antidepressant drug therapy, the anticipated outcomes and benefits of the BRITE trial, the Company's anticipated timing with respect to the release of data from the trial and the Company's belief that it can develop a practical, easy-to-use brain assessment device to help clinicians optimize care for patients suffering from depression. There are a number of factors that could cause actual results to differ materially from those indicated by these forward-looking statements. For example, the completion of the Company's BRITE trial could be delayed and/or the trial could be unsuccessful as a result of various factors including delays in patient enrollment, lower than anticipated retention rates for patients in the trial, negative trial outcomes and the failure of the trial to establish the predictive accuracy of the Company's brain assessment technology in predicting the effectiveness of antidepressant medications. In addition, even if the trial achieves its outcome objectives, the Company may not be able to successfully develop products for the diagnosis and treatment of neurological diseases, such as depression and Alzheimer's disease, achieve widespread market acceptance of any such products that it may develop or to compete with new products or alternative techniques that may be developed by other. There are other factors that could cause the Company's actual results to vary from its forward-looking statements, including without limitation those set forth under the heading "Risk Factors" in the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2007 as filed with the Securities and Exchange Commission. In addition, any forward-looking statements represent the Company's views only as of the date of this press release and should not be relied upon as representing the Company's views as of any subsequent date. While the Company may elect to update forward-looking statements in the future, it specifically disclaims any obligation to do so, even if its expectations change. Therefore, you should not rely on these forward-looking statements as representing the Company's views as of any date subsequent to the date of this press release.

Aspect, Bispectral Index and BIS are registered trademarks of Aspect Medical Systems, Inc. All other trademarks, service marks and company names are the property of their respective owners.