Minor physical anomalies predict bipolar I disorder risk
medwireNews: Study findings confirm the presence of abnormal neurodevelopment in patients with bipolar I disorder and suggest minor physical anomalies (MPAs) could be used to distinguish such patients from mentally healthy individuals.
“MPAs can be regarded as fossilized imprints of early maldevelopment,” comment the study investigators, led by Mladen Mantarkov (Medical University, Plovdiv, Bulgaria). “Their overrepresentation in bipolar I patients is indicative of prenatal insults that increase the risk of disease in later phases of life.”
The researchers found that the frequency distribution of total MPA scores on a slightly modified version of the Waldrop Physical Anomaly Scale was greater among 60 bipolar disorder patients than 103 mentally healthy controls. MPAs included the presence of fine electric hair, low-seated ears, and a curved fifth finger among others.
A total MPA score of at least 4 predicted bipolar I disorder with the best balance for sensitivity and specificity, while a score of at least 5 was best in terms of positive and negative predictive values.
“These values define a ‘border zone’ that clearly distinguishes between patients and controls,” says the team.
Specifically, a total MPA score of at least 4 predicted bipolar I disorder with 78.3% sensitivity and 63.1% specificity, and with positive and negative predictive values of 55.3% and 83.3%, respectively.
For a total MPA score of at least 5, the sensitivity and specificity were 53.3% and 79.6%, respectively, with a positive predictive value of 60.4% and a negative predictive value of 74.5%.
By contrast, mentally healthy individuals predominantly had total MPA scores of 3 or below and rarely had scores of 6 or above.
The researchers note in Psychiatry Research that significantly more bipolar disorder patients than controls presented with very high total MPA scores of 6 or above, but while such a cut-off score was highly specific for bipolar I disorder, at 90.3%, it was not very sensitive, at just 38.3%.
MPAs are “valuable” in discriminating between bipolar I disorder patients and mentally healthy individuals, the team concludes. They “represent markers of aberrant neurodevelopmental processes that probably interact with other genetic and non-genetic risk factors in the etiology of bipolar disorder.”
The researchers suggest that assessment of these and other biological markers in psychiatry “could lead to the identification of composite biomarkers that predict a disease state through the effects of a panel of relevant disease-related markers.”
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lucy Piper, Senior medwireNews Reporter