Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Mar. 24, 2025	Jun. 28, 2024
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40551
Entity Registrant Name	Acumen Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4108129
Entity Address, Address Line One	1210-1220 Washington St.
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	Newton
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02465
City Area Code	617
Local Phone Number	344-4190
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	ABOS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 97.5
Entity Common Stock, Shares Outstanding		60,573,425
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement relating to its 2025 annual meeting of the shareholders, or the 2025 Proxy Statement, are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The 2025 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Entity Central Index Key	0001576885
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false