Precision medicine aims to increase treatment success by tailoring therapies based on individual differences. As in other specialities, psychiatry has attempted to implement approaches from precision medicine by seeking biomarkers to inform treatment and therefore improve prognosis. There is a need for a precision approach in psychiatry as current treatments have been shown to have poor initial success rates for patients within well-defined diagnostic categories [1].
However, in contrast to other areas of medicine, psychiatric patients may not fit any diagnostic category clearly, or may have multiple diagnoses (co-morbidity) [1]. This implies that in psychiatry, diagnostic categories may not be sensitive enough to individual differences or representative of underlying pathologies. Using a symptom-based nosology may impair the search for biomarkers, as diagnostic groups are likely to be heterogeneous in terms of aetiology and pathogenesis. Here, multiple neurobiological mechanisms may lead to similar symptoms or a single mechanism may lead to different symptoms depending on their interaction with other biopsychosocial factors [2] (Fig 1A).