The invention relates to substituted quinazolinone compunds of formula (I) or a pharmaceutically acceptable salt thereof, wherein Y is C or S; m is 1 when Y is C and m is 2 when Y is S; n is 1 or 2; p is from 0 to 3; q is from 1 to 3; Z is -(CRaRb)r- or -SO2-, wherein r is from 0 to 2 and each of Ra and Rb is independently hydrogen or alkyl; X is CH or N; R2 is optionally substituted aryl or optionally substituted heteroaryl; preferably R2 is aryl, and more preferably phenyl optionally substituted by one or more trifluoromethyl, halo, cyano, C1-C6 alkyl or C1-C6 alkoxy; A is -NR3- or -O- wherein R3 is: hydrogen; alkyl, acyl, amidoalkyl, hydroxyalkyl or alkoxyalkyl; the other substituents are defined in the claims. The compounds are modulators of the 5-hydroxytryptamine receptor and are useful for the treatment of diseases of the central nervous system such as psychoses, schizophrenia, manic depressions, neurological disorders, memory disorders, attention deficit disorder, Parkinson’s disease, amyotrophic lateral sclerosis, Alzheimer’s disease, food uptake disorders, and Huntington’s disease.