N-truncated amyloid β (Aβ) 4-42 forms stable aggregates and induces acute and long-lasting behavioral deficits

N -truncated Aβ 4-42 is highly abundant in Alzheimer disease (AD) brain and was the first Aβ peptide discovered in AD plaques. However, a possible role in AD aetiology has largely been neglected. In the present report, we demonstrate that Aβ 4-42 rapidly forms aggregates possessing a high aggregation propensity in terms of monomer consumption and oligomer formation. Short-term treatment of primary cortical neurons indicated that Aβ 4-42 is as toxic as pyroglutamate Aβ 3-42 and Aβ 1-42 . In line with these findings, treatment of wildtype mice using intraventricular Aβ injection induced significant working memory deficits with Aβ 4-42 , pyroglutamate Aβ 3-42 and Aβ 1-42 . Transgenic mice expressing Aβ 4-42 (Tg4-42 transgenic line) developed a massive CA1 pyramidal neuron loss in the hippocampus. The hippocampus-specific expression of Aβ 4-42 correlates well with age-dependent spatial reference memory deficits assessed by the Morris water maze test. Our findings indicate that N -truncated Aβ 4-42 triggers acute and long-lasting behavioral deficits comparable to AD typical memory dysfunction.