New tests for panic attacks and addiction?

According to researchers from the University of Iowa, blood tests could be developed to detect an individual's predisposition to suffer panic attacks or become addicted to substances such as nicotine or cannabis. The research, published in the American Journal of Medical Genetics, draws its conclusions from the differences in the patterns of gene expression observed in the blood samples of participants.

The first study analysed the gene expression in lymphoblasts - immature white cells - of 16 subjects with a panic disorder and 17 without, finding significant differences in gene activity between both groups. Lead author, Dr Robert Philibert, said that, 'panic disorder will no longer be a purely descriptive diagnosis, but, as with cystic fibrosis, Down syndrome and other conditions, a diagnosis based on genetic information' adding that the findings could also 'help us better understand the pathways that initiate, promote and maintain panic disorder'.

Patients with panic disorder suffer frequent panic attacks which include palpitations, shortness of breath, sweating and loss of control. Symptoms are frequently mistaken for heart attacks and patients often end up taking unnecessary cardiac tests. The team is hoping to develop a blood test for commercial use which might help identify individuals who suffer from a panic disorder and which could lead to preventative treatments.

A second study, published in the same journal and using similar techniques, suggests that gene expression could also be used to measure an individual's susceptibility to addictive substances. This study found differences in gene expression between people with and without a history of smoking. The team initially used samples from 6 subjects and 9 controls, using further data from 94 subjects to check for pattern matches at the gene level. A total of 579 genes were more expressed and 584 were less expressed in people who had smoked.

However, Dr Philibert warned that, 'having a particular gene expression change does not by itself predict that a person will act a certain way. However, it can indicate who might have a greater biological basis for engaging in behaviours such as smoking and alcohol or marijuana use' and that 'what matters most is not whether you have a particular gene but whether the gene is expressed, and what other environmental factors may be at play. Genetic variation in and of itself is not deterministic'.

A technique called 'transcription profiling' was used to analyse the blood samples in both studies. This technique involves looking at all the genes at one time. Expressed genes are labelled with fluorescent tags and changes in the intensity of the fluorescence are then used to identify differences in gene expression.