A PSD-95 inhibitor comprising: i. a first peptide (P 1 ) comprising or consisting of the amino acid sequence X 2 TX 3 V (SEQ ID NO: 53), wherein X 2 is selected from the group consisting of E and S; X 3 is selected from the group consisting of L, T, V, R and D; ii. a second peptide (P 2 ) comprising or consisting of the amino acid sequence X 5 TX 6 V (SEQ ID NO: 55), wherein X 5 is selected from the group consisting of E and S; X 6 is selected from the group consisting of L, T, V, R and D; and iii. a Cell Penetrating Peptide (CPP) selected from the group consisting of: a) a poly-L-arginine peptide (poly-Arg) consisting of 3 to 9 L-arginine residues; b) yGrkkrrqrrr (SEQ ID NO: 9, D-TAT); c) RQIKIWFQNRRMKWKK (SEQ ID NO: 14, L-Pen); d) rqikiwfqnrrmkwkk (SEQ ID NO: 15, D-Pen); e) RKKRRRESRKKRRRES (SEQ ID NO: 17, L-DPV3); f) LLIILRRRIRKQAHAHSK (SEQ ID NO: 18, L-pVEC); g) KLALKLALKALKAALKLA (SEQ ID NO: 16, L-MAP); h) PLIYLRLLRGQF (SEQ ID NO: 19, L-TP2); i) |(Dap)KAPETALD| (SEQ ID NO: 21, MiniAp4); and j) |Ff(Nal2)RrRrQ|GABA-K (SEQ ID NO: 22, CPP12), wherein the CPP is linked to a linker via its C-terminal, and P 1 and P 2 are conjugated to the linker via their N-termini, and the PSD-95 inhibitor has the general structure of Formula (I): or a pharmaceutically acceptable salt thereof. i. a first peptide (P 1 ) comprising or consisting of the amino acid sequence X 2 TX 3 V (SEQ ID NO: 53), wherein X 2 is selected from the group consisting of E and S; X 3 is selected from the group consisting of L, T, V, R and D; X 2 is selected from the group consisting of E and S; X 3 is selected from the group consisting of L, T, V, R and D; ii. a second peptide (P 2 ) comprising or consisting of the amino acid sequence X 5 TX 6 V (SEQ ID NO: 55), wherein X 5 is selected from the group consisting of E and S; X 6 is selected from the group consisting of L, T, V, R and D; and X 5 is selected from the group consisting of E and S; X 6 is selected from the group consisting of L, T, V, R and D; and iii. a Cell Penetrating Peptide (CPP) selected from the group consisting of: a) a poly-L-arginine peptide (poly-Arg) consisting of 3 to 9 L-arginine residues; b) yGrkkrrqrrr (SEQ ID NO: 9, D-TAT); c) RQIKIWFQNRRMKWKK (SEQ ID NO: 14, L-Pen); d) rqikiwfqnrrmkwkk (SEQ ID NO: 15, D-Pen); e) RKKRRRESRKKRRRES (SEQ ID NO: 17, L-DPV3); f) LLIILRRRIRKQAHAHSK (SEQ ID NO: 18, L-pVEC); g) KLALKLALKALKAALKLA (SEQ ID NO: 16, L-MAP); h) PLIYLRLLRGQF (SEQ ID NO: 19, L-TP2); i) |(Dap)KAPETALD| (SEQ ID NO: 21, MiniAp4); and j) |Ff(Nal2)RrRrQ|GABA-K (SEQ ID NO: 22, CPP12), a) a poly-L-arginine peptide (poly-Arg) consisting of 3 to 9 L-arginine residues; b) yGrkkrrqrrr (SEQ ID NO: 9, D-TAT); c) RQIKIWFQNRRMKWKK (SEQ ID NO: 14, L-Pen); d) rqikiwfqnrrmkwkk (SEQ ID NO: 15, D-Pen); e) RKKRRRESRKKRRRES (SEQ ID NO: 17, L-DPV3); f) LLIILRRRIRKQAHAHSK (SEQ ID NO: 18, L-pVEC); g) KLALKLALKALKAALKLA (SEQ ID NO: 16, L-MAP); h) PLIYLRLLRGQF (SEQ ID NO: 19, L-TP2); i) |(Dap)KAPETALD| (SEQ ID NO: 21, MiniAp4); and j) |Ff(Nal2)RrRrQ|GABA-K (SEQ ID NO: 22, CPP12), wherein the CPP is linked to a linker via its C-terminal, and P 1 and P 2 are conjugated to the linker via their N-termini, and the PSD-95 inhibitor has the general structure of Formula (I): or a pharmaceutically acceptable salt thereof. <EOS>