The present invention is concerned with pharmaceutical compositions comprising a carrier and as first active ingredient an atypical antipsychotic agent (I) and as second active ingredient an acetylcholinesterase inhibitor (II), each in an amount producing a therapeutically beneficial effect in patients suffering from psychosis, or Alzheimer's disease or related dementias. Said therapeutically beneficial effect can be a synergistic effect on the cognitive functioning of patients suffering from Alzheimer's disease or related dementias or the prevention of the further deterioration of cognition in said patients, or the reduction of adverse effects associated with the one of the active ingredients by the other of the active ingredients.
