The use of a combined selective 5-HT6/5-HT2A antagonist of formula V, wherein said compound has an affinity for the 5-HT6 receptor with pKi value of greater than or equal to 8, an affinity for the 5-HT2A receptor with pKi value of greater than or equal to 8, and has a selectivity of at least 30 over the dopamine D2 receptor, the histamine H1 receptor, and the muscarinic M1 and M2 receptors for the manufacture of a medicament for treating a disease state associated with a cognitive disorder, selected from the group consisting of learning disabilities, mild cognitive impairment, age-related cognitive decline, cerebral senility, vascular dementia, AIDS-associated dementia, electric shock induced amnesia, memory impairment associated with anxiety, Down's syndrome, stroke and traumatic brain injury. wherein u is from 0 to 3; v is from 1 to 3; Ar is optionally substituted aryl or optionally substituted heteroaryl; each R 16 is independently halo, alkyl, haloalkyl, cyano, -SO 2 R f, -C(=O)-NR g R h, - SR g, -C(=O)-R g, wherein each R f, R g and R h and is independently hydrogen or alkyl; R 17 and R 18 each independently is hydrogen or alkyl, or R 17 and R 18 together may form =NR i wherein R i is hydrogen or alkyl; R 19 and R 20 each independently is hydrogen or alkyl, or one of R 19 and R 20 is hydrogen and the other is an optionally substituted heteroaryl, or R 19 and R 20 together with the nitrogen to which they are attached may form an amidinyl group, a urea group, a guanidinyl group, or a five-or six-membered ring that optionally includes an additional heteroatom selected from O, N and S, or one of R 19 and R 20 and one of R 17 and R 18 together with the atoms to which they are attached may form a five- or six-membered ing that optionally includes an additional heteroatom selected from O, N and S; and the pharmaceutically acceptable acid addition salts thereof. u is from 0 to 3; v is from 1 to 3; Ar is optionally substituted aryl or optionally substituted heteroaryl; each R 16 is independently halo, alkyl, haloalkyl, cyano, -SO 2 R f, -C(=O)-NR g R h, - SR g, -C(=O)-R g, wherein each R f, R g and R h and is independently hydrogen or alkyl; R 17 and R 18 each independently is hydrogen or alkyl, or R 17 and R 18 together may form =NR i wherein R i is hydrogen or alkyl; R 19 and R 20 each independently is hydrogen or alkyl, or one of R 19 and R 20 is hydrogen and the other is an optionally substituted heteroaryl, or R 19 and R 20 together with the nitrogen to which they are attached may form an amidinyl group, a urea group, a guanidinyl group, or a five-or six-membered ring that optionally includes an additional heteroatom selected from O, N and S, or one of R 19 and R 20 and one of R 17 and R 18 together with the atoms to which they are attached may form a five- or six-membered ing that optionally includes an additional heteroatom selected from O, N and S; and the pharmaceutically acceptable acid addition salts thereof. Ar is optionally substituted aryl or optionally substituted heteroaryl; each R 16 is independently halo, alkyl, haloalkyl, cyano, -SO 2 R f, -C(=O)-NR g R h, - SR g, -C(=O)-R g, wherein each R f, R g and R h and is independently hydrogen or alkyl; R 17 and R 18 each independently is hydrogen or alkyl, or R 17 and R 18 together may form =NR i wherein R i is hydrogen or alkyl; R 19 and R 20 each independently is hydrogen or alkyl, or one of R 19 and R 20 is hydrogen and the other is an optionally substituted heteroaryl, or R 19 and R 20 together with the nitrogen to which they are attached may form an amidinyl group, a urea group, a guanidinyl group, or a five-or six-membered ring that optionally includes an additional heteroatom selected from O, N and S, or one of R 19 and R 20 and one of R 17 and R 18 together with the atoms to which they are attached may form a five- or six-membered ing that optionally includes an additional heteroatom selected from O, N and S; and the pharmaceutically acceptable acid addition salts thereof.