Minor physical anomalies in schizophrenia and bipolar I disorder and the neurodevelopmental continuum of psychosis

Abstract

Objectives: Minor physical anomalies (MPAs) have been investigated by numerous studies in patients with schizophrenia in support of the neurodevelopmental hypothesis of the disorder, but have rarely been examined in patients with bipolar disorder or in direct comparisons between the two conditions. The main objective of the present study was to compare the prevalence of MPAs in psychiatrically healthy controls, patients with bipolar I disorder, and patients with schizophrenia.

Methods: A slightly modified version of the Waldrop Physical Anomaly Scale was used to assess MPAs in psychiatrically healthy controls (n = 103), patients with bipolar I disorder (n = 61), and patients with schizophrenia (n = 128).

Results: In five out of six topographic regions (mouth, feet, head, eyes, and ears) there was a pattern of lowest regional MPA scores in controls, intermediate in bipolar I disorder, and highest in schizophrenia. The cephalofacial composite score and the total MPA score showed the same pattern, with all between-group differences being statistically significant. Seven individual MPAs in the discriminant analysis model contributed independently to the prediction of the triple-dependent status of 'psychiatrically healthy control, bipolar I disorder patient, schizophrenia patient': high/arched palate, fine electric hair, large gap between first and second toes, third toe ≥ second toe, epicanthus, malformed ears, and furrowed tongue.

Conclusions: Our findings support the existence of a continuum of neurodevelopmental adversity within the clinical spectrum of psychosis, with bipolar I disorder occupying an intermediate position between psychiatric health and schizophrenia.

Keywords: bipolar I disorder; minor physical anomalies; neurodevelopmental hypothesis; psychotic continuum; schizophrenia.