Behavioural and psychological symptoms of dementia (BPSD) are common and have significant implications for patients and caregivers. Non‐pharmacological interventions (NPI) have shown to be effective in the management of BPSD. However, the use of antipsychotics to treat BPSD remains ubiquitous. This retrospective, before–after study aimed to examine whether a nurse mentoring programme promoting NPI for BPSD management had a significant association with the use of antipsychotics in older adults with major neurocognitive disorders residing in different settings. Results obtained from the medical files of 134 older adults having benefitted from the mentoring programme demonstrate that this intervention significantly reduced BPSD. The effect on antipsychotics use was modest: a 10% reduction in the use of antipsychotics has been observed among patients for which the NPI were effective. However, the use of antipsychotics remained widespread despite the nursing recommendations of the mentoring team of the Center of Excellence on Aging in Quebec (CEVQ).