Alto Neuroscience Presents New Data at the 64th Annual Meeting of the American College of Neuropsychopharmacology

– Data presented demonstrate robust validation of Theta ITC as an EEG biomarker of CIAS and support its use as the primary outcome in the ongoing Phase 2 POC study of ALTO-101 –

– Detailed analysis of data from the completed ALTO-203 Phase 2 proof-of-concept study demonstrates clear pharmacodynamic effects and suggests utility of ALTO-203 in indications with excessive daytime sleepiness and/or deficits in sustained attention –

MOUNTAIN VIEW, Calif.--(BUSINESS WIRE)--Alto Neuroscience, Inc. (“Alto”) (NYSE: ANRO), a clinical-stage biopharmaceutical company focused on the development of novel precision medicines for neuropsychiatric disorders, today announced multiple presentations highlighting new data and analyses supporting the Company’s development programs at the 64th annual meeting of the American College of Neuropsychopharmacology (ACNP) held January 12-15, 2026.

“We are pleased to have the opportunity to showcase the breadth and depth of our precision psychiatry platform at ACNP, which is one of the most highly regarded conferences in psychiatry,” said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience. “We are excited for the clinical milestones expected this year and continue to be encouraged by the strength of the analyses leveraging our platform.”

The details of each presentation are as follows:

Presentation Title: Event-Related Theta Responses as Candidate Markers of Cognitive Impairment​ Associated with Schizophrenia: Independent Replication of Case-Control Differences and Cognitive Associations in a Large Patient Sample

Key Takeaways:

• This new analysis of an independent data set consisting of 155 individuals with schizophrenia and 272 healthy control subjects validated the prior findings by Alto supporting Theta-ITC as the most robust EEG marker for detecting case-control differences.
• Theta-ITC shows consistent association with key cognitive measures being evaluated in Alto’s ongoing CIAS trial.
• The results represent a second large independent replication and further strengthen the relevance of Theta-ITC as a key biomarker endpoint to evaluate potential effects in CIAS.

Presentations Title: Prospective replication of an EEG biomarker for predicting changes in attention with ALTO-203, an H3 inverse agonist​

Key Takeaways:

• ALTO-203 improves sustained attention, decreases theta/beta ratio, and the greatest improvements in sustained attention occur in individuals with abnormal theta/beta ratios.
• ALTO-203 improved wakefulness, without changes in sleep efficiency or wake after sleep onset.
• These findings replicate prior data from a Phase 1 study of ALTO-203 in healthy subjects and suggest ALTO-203 may be best suited for indications with excessive daytime sleepiness/hypersomnolence and/or deficits in sustained attention.

Presentation Title: An EEG Biomarker Predicting Placebo Response in Major Depressive Disorder: Development, Prospective Validation, and Implications for Enhancing Detection of Treatment Effects​

Key Takeaways:

• Alto developed and validated an EEG biomarker capable of predicting treatment response across various interventions and independent data sets in depression.
• The EEG biomarker was used to analyze data from two randomized controlled trials, which resulted in enhanced treatment effect compared to the analysis without accounting for individual differences.
• These analyses demonstrate the potential to use an EEG biomarker to improve signal detection in studies of interventions in MDD.

About Alto Neuroscience

Alto Neuroscience is a clinical-stage biopharmaceutical company with a mission to redefine psychiatry by leveraging neurobiology to develop personalized and highly effective treatment options. Alto’s Precision Psychiatry Platform™ measures brain biomarkers by analyzing EEG activity, neurocognitive assessments, wearable data, and other factors to better identify which patients are more likely to respond to Alto product candidates. Alto’s clinical-stage pipeline includes novel drug candidates in bipolar depression, major depressive disorder, treatment resistant depression (TRD), and schizophrenia, and other mental health conditions.

Forward-Looking Statements

This press release may contain forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “expects,” “plans,” “will” and variations of these words or similar expressions that are intended to identify forward-looking statements, although not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, statements regarding Alto’s expectations about the potential benefits, activity, and effectiveness of its product candidates, biomarkers, and Precision Psychiatry Platform (“Platform”); statements regarding Alto’s expectations for the design, progress and results of its ongoing Phase 2 POC trial of ALTO-101 in CIAS; the reproducibility of any favorable results seen in the exploratory Phase 2 POC trial of ALTO-203; and Alto’s expectations with regard to the design and results of its clinical trials. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements as a result of various factors, including uncertainties inherent in the initiation, progress and completion of clinical trials and other important factors, any of which could cause Alto’s actual results to differ from those contained in the forward-looking statements, which are described in greater detail in the section titled “Risk Factors” in Alto’s Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2025 filed with the Securities and Exchange Commission (“SEC”) as well as in other filings Alto may make with the SEC in the future. Any forward-looking statements contained in this press release speak only as of the date hereof, and Alto expressly disclaims any obligation to update any forward-looking statements contained herein, whether because of any new information, future events, changed circumstances or otherwise, except as required by law.

Availability of Information on Alto’s Website

Alto routinely uses its investor relations website to post presentations to investors and other important information, including information that may be material. Accordingly, Alto encourages investors and others interested in Alto to review the information it makes public on its investor relations website.