“Conversion therapy” —technically called sexual orientation and gender identity and expression change efforts (SOGIECE)— promises, in theory, to conform people to heterosexual and cisgender norms. In practice, having reviewed more than six thousand studies, the accumulated evidence shows not change but harm. That is what the largest systematic review published to date documents.
An international research team searched eight bibliographic databases for every published empirical study that quantified the effect of these practices. Of 6,309 screened articles, 130 met the eligibility criteria. The balance is unequivocal: among the 86 prospective studies analysed, at least one form of harm was present in 77.91% of them.
What counts as harm
The review goes far beyond generic distress. It defined five specific types of harm: the use of aversive techniques (unpleasant stimuli to punish unwanted attraction or identity); lack of informed consent or coercion; increased psychopathology; negative changes in life functioning and quality of life; and deterioration of personal relationships.
The finding is no less significant for being expected. 68.18% of retrospective studies also found a significant association between exposure to these therapies and the presence of harm. In short, the evidence points consistently in the same direction: these interventions do not achieve what they promise, and they leave a mark.
Two generations of studies
The analysis distinguishes two waves of research with very different profiles. The first, prospective in design, has a mean publication year of 1974; the second, retrospective, dates on average from 2012. The gap of almost four decades reflects not only a change in methods, but also a shift in clinical practice itself and in the scientific standing of these therapies, now rejected by the world’s main medical societies.
Why this review matters
Although the professional rejection of conversion therapies is not new, a systematic and quantified update of the state of the science was missing. This review does more than confirm the association between these practices and harm: it orders and describes the methodological quality of the evidence on which that conclusion rests. In a context where these therapies are still applied in some countries, having a rigorous and recent synthesis is a strong argument for regulations that prohibit them.
The conclusion emerging from the data is as clear as it is uncomfortable for their defenders: efforts to change identity or orientation do not achieve their stated goal, and the cost in mental wellbeing and quality of life is documented. Science has now put it in writing.
