An antibody or antigen-binding fragment thereof which specifically binds to L-isoAsp7 Aβ, wherein: (i) the K D of the interaction between the antibody and SEQ ID NO: 44 is at least 10 times less than the K D of the interaction between the antibody and SEQ ID NO: 8 and the K D is determined by surface plasmon resonance at 25 °C, (ii) the K D of the interaction of the antibody or antigen-binding fragment and SEQ ID NO: 44 is less than 100 nM and the K D is determined by surface plasmon resonance at 25 °C; and (iii) wherein the antibody or antigen-binding fragment thereof comprises a light chain variable region and a heavy chain variable region, wherein said VL comprises LCDR1, LCDR2 and LCDR3 polypeptides and VH comprises HCDR1, HCDR2 and HCDR3 polypeptides which are selected from the group consisting of: (a) LCDR1 is KSSQSLLNSRNRKNYLA (SEQ ID NO: 9), LCDR2 is WASTRDS (SEQ ID NO: 11), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is ALWASGNTDYSSTLMS (SEQ ID NO: 15), and HCDR3 is DRGILTGGYFDV (SEQ ID NO: 17); (b) LCDR1 is KSSQSLFNSRTRKNYVA (SEQ ID NO: 27), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is KQSYNLRA (SEQ ID NO: 30), HCDR1 is GFTFTDYYMS (SEQ ID NO: 32), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35); (c) LCDR1 is KSSQSLLNX 1 RX 2 RKNYLA (SEQ ID NO: 10), LCDR2 is WASTRX 3 S (SEQ ID NO: 12), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is X 4 LWASGX 5 TDYX 6 SX 7 LMS (SEQ ID NO: 16), and HCDR3 is DRGIX 8 TGGYFDV (SEQ ID NO: 18), wherein X 1 is S or R, X 2 is N or T, X 3 is D or E, X 4 is A or V, X 5 is N or R, X 6 is S or N, X 7 is T or A, and X 8 is L, T or M; and (d) LCDR1 is KSSQX 1 LX 2 NSRTRKNYX 3 A (SEQ ID NO: 28), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is X 4 QSYNLRX 5 (SEQ ID NO: 31), HCDR1 is GFTFX 6 DYYMX 7 (SEQ ID NO: 33), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35), wherein X 1 is S or N, X 2 is F or L, X 3 is V or L, X 4 is K or M, X 5 is A or T, X 6 is T or S, and X 7 is S or N. (i) the K D of the interaction between the antibody and SEQ ID NO: 44 is at least 10 times less than the K D of the interaction between the antibody and SEQ ID NO: 8 and the K D is determined by surface plasmon resonance at 25 °C, (ii) the K D of the interaction of the antibody or antigen-binding fragment and SEQ ID NO: 44 is less than 100 nM and the K D is determined by surface plasmon resonance at 25 °C; and (iii) wherein the antibody or antigen-binding fragment thereof comprises a light chain variable region and a heavy chain variable region, wherein said VL comprises LCDR1, LCDR2 and LCDR3 polypeptides and VH comprises HCDR1, HCDR2 and HCDR3 polypeptides which are selected from the group consisting of: (a) LCDR1 is KSSQSLLNSRNRKNYLA (SEQ ID NO: 9), LCDR2 is WASTRDS (SEQ ID NO: 11), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is ALWASGNTDYSSTLMS (SEQ ID NO: 15), and HCDR3 is DRGILTGGYFDV (SEQ ID NO: 17); (b) LCDR1 is KSSQSLFNSRTRKNYVA (SEQ ID NO: 27), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is KQSYNLRA (SEQ ID NO: 30), HCDR1 is GFTFTDYYMS (SEQ ID NO: 32), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35); (c) LCDR1 is KSSQSLLNX 1 RX 2 RKNYLA (SEQ ID NO: 10), LCDR2 is WASTRX 3 S (SEQ ID NO: 12), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is X 4 LWASGX 5 TDYX 6 SX 7 LMS (SEQ ID NO: 16), and HCDR3 is DRGIX 8 TGGYFDV (SEQ ID NO: 18), wherein X 1 is S or R, X 2 is N or T, X 3 is D or E, X 4 is A or V, X 5 is N or R, X 6 is S or N, X 7 is T or A, and X 8 is L, T or M; and (d) LCDR1 is KSSQX 1 LX 2 NSRTRKNYX 3 A (SEQ ID NO: 28), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is X 4 QSYNLRX 5 (SEQ ID NO: 31), HCDR1 is GFTFX 6 DYYMX 7 (SEQ ID NO: 33), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35), wherein X 1 is S or N, X 2 is F or L, X 3 is V or L, X 4 is K or M, X 5 is A or T, X 6 is T or S, and X 7 is S or N. (a) LCDR1 is KSSQSLLNSRNRKNYLA (SEQ ID NO: 9), LCDR2 is WASTRDS (SEQ ID NO: 11), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is ALWASGNTDYSSTLMS (SEQ ID NO: 15), and HCDR3 is DRGILTGGYFDV (SEQ ID NO: 17); (b) LCDR1 is KSSQSLFNSRTRKNYVA (SEQ ID NO: 27), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is KQSYNLRA (SEQ ID NO: 30), HCDR1 is GFTFTDYYMS (SEQ ID NO: 32), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35); (c) LCDR1 is KSSQSLLNX 1 RX 2 RKNYLA (SEQ ID NO: 10), LCDR2 is WASTRX 3 S (SEQ ID NO: 12), LCDR3 is KQSYNLRT (SEQ ID NO: 13), HCDR1 is GFSLTSYGVH (SEQ ID NO: 14), HCDR2 is X 4 LWASGX 5 TDYX 6 SX 7 LMS (SEQ ID NO: 16), and HCDR3 is DRGIX 8 TGGYFDV (SEQ ID NO: 18), wherein X 1 is S or R, X 2 is N or T, X 3 is D or E, X 4 is A or V, X 5 is N or R, X 6 is S or N, X 7 is T or A, and X 8 is L, T or M; and (d) LCDR1 is KSSQX 1 LX 2 NSRTRKNYX 3 A (SEQ ID NO: 28), LCDR2 is WASTRES (SEQ ID NO: 29), LCDR3 is X 4 QSYNLRX 5 (SEQ ID NO: 31), HCDR1 is GFTFX 6 DYYMX 7 (SEQ ID NO: 33), HCDR2 is FIRNKANGYTTEYSASVKG (SEQ ID NO: 34), and HCDR3 is DIPTIMDY (SEQ ID NO: 35), wherein X 1 is S or N, X 2 is F or L, X 3 is V or L, X 4 is K or M, X 5 is A or T, X 6 is T or S, and X 7 is S or N.