Massey University's Sione Vaka spent most of his career researching cultural understandings of mental health and the use of appropriate tools.
Dr Vaka is in Tonga attending the country's first mental health symposium and said the biggest problem sufferers have was dealing with cultural stigma.
"That there might be something wrong that the family has done, some sort of sin or some sort of curse that happens to them," he said.
"It does not only label the individual but it labels the family and sometimes it goes through the village as well and with this stigma it creates a barrier and people don't want to go to mental health services."
RNZI reports Dr Vaka has created an alternative model of care based on a communal fishing techniques called Uloa, which he said could be implemented in Tonga.
He said it would involve communication between both traditional and contemporary health workers.