Disclosed are an alpha 7 nAChR receptor modulator compound, 4-(5-(4-chlorophenyl)-2-(2-cyclopropylacetyl)-1,4-dimethyl-1H-pyrrol-3-yljbenzenesulfonamide, its tautomeric form, its pharmaceutically acceptable salts, pharmaceutical compositions comprising the compound or a salt thereof, and a method of treating various diseases, disorders or conditions, for example, Alzheimer's disease, mild cognitive impairment, senile dementia, vascular dementia, dementia of Parkinson's disease, and attention deficit disorder.