Of the more than 1200 partners, family members and friends of psychopaths who were surveyed, 93% reported their behaviour was just as bad, if not worse, than when they were younger.
Co-author and psychology professor Martin Sellbom said the research focused on people with antisocial personality disorder/psychopathy who were over 50.
"There is a general idea that offenders burn out and change their antisocial ways.
"But this study shows that those with psychopathic traits very much remain the same past age 50, and some even become worse as they get older with respect to manipulation, deceit, and abuse.
"This research gives a voice to the victims of psychopathy, providing a general indication of the degree to which victims are affected.
"Most of the time we focus on the individuals with such traits, and their biased perspectives."
According to those surveyed, 935 individuals showed levels of disordered traits considered indicative of antisocial personality disorder or psychopathy.
Respondents said 99% were manipulative, 94% engaged in antisocial behaviour, 93% were emotionally abusive, 89% were psychologically abusive, 58% were financially abusive and 47% were violent.
Many respondents provided narrative descriptions of what they witnessed and experienced.
One woman said the older her ex-husband got, the more abusive he became.
"He lied, cheated, used, and stole. As he aged, he seemed to care less about hiding his behaviour, and he seemed to openly enjoy being cruel."
Another respondent said nothing about her mother ever changed.
"She exploits, lies, throws tantrums, rages, abandons, pouts, defames, threatens, and would still be physically violent if she had the physical strength."
Other significant harms caused by the over-50 individuals included losing money (68% of respondents) and incurring debt (45%).
Twenty-six percent of respondents had been physically abused or injured and 27% had had their lives threatened.
Prof Sellbom said those behaviours caused widespread psychological harm to family members and friends.
Nearly 90% of survey respondents had become anxious or depressed, 76% said the stress of the involvement had made them ill, 70% said they had suffered post-traumatic stress disorder and 31% had considered or attempted suicide.
Lead author and Lovefraud Education and Recovery founder Donna Andersen said the research showed people with antisocial personality disorder or psychopathy never stopped their manipulative and deceptive behaviour.
Anyone waiting for a senior sociopath to grow up or calm down should accept they would not change.
