Why are so few antipsychotic drugs licensed for Alzheimer's disease related behavioral and psychological symptoms?

Alzheimer’s disease is the most common type of dementia. The progressive nature of the disease represents a challenge for clinicians, aiming to ensure an adequate treatment and support to the patient and the caregivers. Together with the impairment in several cognitive domains, progressively worsening, behavioral symptoms frequently occur. Among them, agitation and aggression pose great management difficulty; the therapeutic approach could be nonpharmacological and/or pharmacological. Unfortunately, even though the non-pharmacological approach is safer for the patient, the data about efficacy are sparse and limited. The pharmacological approach with antipsychotic drugs, together with heterogeneous results about efficacy, leads to higher rate of complications. For this reason, antipsychotic drugs are not licensed for the use in behavioral disturbances in dementia, apart from Risperidone; other drugs are usually prescribed off-label. All considered, the treatment of behavioral symptoms in dementia represents a great challenge for clinicians, especially when treating complex or frail patients.