Exhibit 15.1

Consent of Independent Registered Public Accounting Firm

Addex Therapeutics Ltd

Geneva, Switzerland

We hereby consent to the incorporation by reference in the Registration Statements on Form F-3 (No. 333-291644) and Form S-8 (No. 333-255124 and No.333-272515) of Addex Therapeutics Ltd (the Company) of our report dated May 15, 2026, relating to the consolidated financial statements appearing in the Company’s Annual Report on Form 20-F for the year ended December 31, 2025. Our report contains an explanatory paragraph regarding the Company’s ability to continue as a going concern.

BDO AG

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Consent of Independent Registered Public Accounting Firm

Neurosterix US Holding LLC

Delaware, USA

We hereby consent to the incorporation by reference in the Registration Statements on Form F-3 (No. 333-291644) and Form S-8 (No. 333-255124 and No.333-272515) of our report dated May 13, 2026, relating to the Neurosterix US Holding LLC consolidated financial statements appearing in Addex Therapeutics Ltd’s Annual Report on Form 20-F for the year ended December 31, 2025.

BDO AG

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