DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Acumen Pharmaceuticals, Inc. (“Acumen” or the “Company”) was incorporated in 1996 in the state of Delaware. Acumen is a clinical-stage biopharmaceutical company developing a novel disease-modifying approach targeting what the Company believes to be a key underlying cause of Alzheimer’s disease (“AD”). Alzheimer’s disease is a progressive neurodegenerative disease of the brain that leads to loss of memory and cognitive functions and ultimately results in death. The Company’s scientific founders pioneered research on soluble amyloid-beta oligomers (“AßOs”), which are globular assemblies of the amyloid-beta (“Aß”) peptide that are distinct from Aß monomers and amyloid plaques. Based on decades of research and supporting evidence, AßOs have gained increasing scientific acceptance as a primary toxin involved in the initiation and propagation of AD pathology. The Company is currently focused on advancing a targeted immunotherapy drug candidate, sabirnetug, in its Phase 2 ALTITUDE-AD clinical trial, and expects to announce top-line results in late 2026. ALTITUDE-AD is a randomized, double-blind, placebo-controlled, three-arm clinical trial designed to evaluate the clinical efficacy, safety and tolerability of sabirnetug with up to 180 participants per arm for a total of 542 participants with mild cognitive impairment or mild dementia due to AD. Sabirnetug is a recombinant humanized immunoglobulin gamma 2 monoclonal antibody that was designed to selectively target AßOs. In July 2023, the Company announced topline results from its Phase 1 INTERCEPT-AD clinical trial of sabirnetug, which demonstrated that sabirnetug met the primary and secondary objectives of this clinical trial in 62 participants with early AD. In addition, the Company is investigating a subcutaneous dosing option of sabirnetug, as well as a blood-brain barrier-penetrating, Aß oligomer-targeted Enhanced Brain Delivery (EBD™) therapy for AD. The Company is subject to the uncertainty of whether its intellectual property will develop into successful commercial products. Liquidity, Capital Resources and Going Concern In accordance with Accounting Standards Codification (“ASC”) 205-40, Presentation of Financial Statements-Going Concern, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern. The Company has incurred operating losses since inception. As of December 31, 2025, the Company had an accumulated deficit of $446.5 million and had cash and cash equivalents and marketable securities of $116.9 million. The Company expects to incur additional losses for the foreseeable future as it continues its research and development activities and will need to raise additional capital to fully implement its business plan and to fund its operations. Until such time, if ever, as the Company can generate revenue sufficient to achieve profitability, the Company expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. There can be no assurance that any such financing will be available to the Company at adequate levels and on a timely basis, or such agreements may not be available on terms acceptable to the Company, or at all. The Company may be required to delay, limit, reduce or terminate its product discovery and development activities or future commercialization efforts if it is unable to maintain sufficient financial resources, and its business, financial condition and results of operations will be materially and adversely affected. The Company expects that its current balance of cash and cash equivalents and marketable securities may not be sufficient to fund its operations for at least 12 months from the date of issuance of these financial statements. The Company’s cash forecast contains estimates and assumptions related to its ongoing clinical trial and other research and development expenses, and the Company cannot predict the amount or timing of all expenditures with certainty. Accordingly, the Company has concluded that substantial doubt exists about its ability to continue as a going concern. The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business, and do not include any adjustments relating to recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might be necessary, should the Company be unable to continue as a going concern.

Acumen Pharmaceuticals, Inc. (“Acumen” or the “Company”) was incorporated in 1996 in the state of Delaware. Acumen is a clinical-stage biopharmaceutical company developing a novel disease-modifying approach targeting what the Company believes to be a key underlying cause of Alzheimer’s disease (“AD”). Alzheimer’s disease is a progressive neurodegenerative disease of the brain that leads to loss of memory and cognitive functions and ultimately results in death. The Company’s scientific founders pioneered research on soluble amyloid-beta oligomers (“AßOs”), which are globular assemblies of the amyloid-beta (“Aß”) peptide that are distinct from Aß monomers and amyloid plaques. Based on decades of research and supporting evidence, AßOs have gained increasing scientific acceptance as a primary toxin involved in the initiation and propagation of AD pathology. The Company is currently focused on advancing a targeted immunotherapy drug candidate, sabirnetug, in its Phase 2 ALTITUDE-AD clinical trial, and expects to announce top-line results in late 2026. ALTITUDE-AD is a randomized, double-blind, placebo-controlled, three-arm clinical trial designed to evaluate the clinical efficacy, safety and tolerability of sabirnetug with up to 180 participants per arm for a total of 542 participants with mild cognitive impairment or mild dementia due to AD. Sabirnetug is a recombinant humanized immunoglobulin gamma 2 monoclonal antibody that was designed to selectively target AßOs. In July 2023, the Company announced topline results from its Phase 1 INTERCEPT-AD clinical trial of sabirnetug, which demonstrated that sabirnetug met the primary and secondary objectives of this clinical trial in 62 participants with early AD. In addition, the Company is investigating a subcutaneous dosing option of sabirnetug, as well as a blood-brain barrier-penetrating, Aß oligomer-targeted Enhanced Brain Delivery (EBD™) therapy for AD.

In accordance with Accounting Standards Codification (“ASC”) 205-40, Presentation of Financial Statements-Going Concern, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern. The Company has incurred operating losses since inception. As of December 31, 2025, the Company had an accumulated deficit of $446.5 million and had cash and cash equivalents and marketable securities of $116.9 million. The Company expects to incur additional losses for the foreseeable future as it continues its research and development activities and will need to raise additional capital to fully implement its business plan and to fund its operations. Until such time, if ever, as the Company can generate revenue sufficient to achieve profitability, the Company expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. There can be no assurance that any such financing will be available to the Company at adequate levels and on a timely basis, or such agreements may not be available on terms acceptable to the Company, or at all. The Company may be required to delay, limit, reduce or terminate its product discovery and development activities or future commercialization efforts if it is unable to maintain sufficient financial resources, and its business, financial condition and results of operations will be materially and adversely affected. The Company expects that its current balance of cash and cash equivalents and marketable securities may not be sufficient to fund its operations for at least 12 months from the date of issuance of these financial statements. The Company’s cash forecast contains estimates and assumptions related to its ongoing clinical trial and other research and development expenses, and the Company cannot predict the amount or timing of all expenditures with certainty. Accordingly, the Company has concluded that substantial doubt exists about its ability to continue as a going concern.