Anxiety disorders
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Division of Molecular Biology & Human Genetics


​Anxiety disorders


Psychiatric disorders are among the most widespread and disabling of all illnesses in developed societies. In terms of their overall prevalence, economic burden and the long-sustained problems they cause, these disorders exceed most forms of ill health. In the United States alone, the estimated collective costs per year for these disorders are approximately $400 billion. Moreover, according to the World Health Organization, mental illness tops the the disability adjusted life years (DALY) scale, comprising 37% of healthy years lost due to all non-communicable diseases (such as cardiovascular disease, chronic respiratory disease, cancer and diabetes) (WHO, 2011). These statistics emphasise the severity and prevalence and psychiatric disorders and stress the importance of getting a clear handle on their pathophysiologies, in order to develop better diagnostic tools and treatment modalities.

Reference: World Health Organization: Global Status Report on Non-communicable Diseases. Geneva, 2010



Our research team is involved primarily in investigating the molecular aetiology of posttraumatic stress disorder (PTSD). PTSD is a severe, chronic and debilitating psychiatric disorder that can occur after exposure to a traumatic event (this is an event which causes intense fear, helplessness and horror, including (but certainly not limited to) rape, a physical attack, hijacking, motor vehicle accident and combat exposure). PTSD symptoms usually appear three months after the traumatic experience has taken place. These symptoms are divided into three main clusters: intrusive thoughts, avoidance/numbing and hyperarousal. Some of the symptoms associated with each of these clusters are as follows:

  • Intrusive thoughts – flashbacks; reliving the traumatic event; nightmares about the trauma
  • Avoidance/numbing – avoidance of reminders related to the trauma; avoiding previously enjoyable activities; trouble concentrating; problems with memory
  • Hyperarousal– anger; irritability; easily startled/frightened

Although approximately 50% to 90% of individuals will be exposed to a traumatic life event, only approximately 7-8% of these individuals will develop PTSD. Family and twin studies have implicated the role of genetic factors in contributing to the development of PTSD. This has generated a large amount of interest in identifying not only the risk factors involved in the development of the disorder, but also the factors that confer resiliency against developing PTSD.

We are applying an integrated systems biology approach, where we combine clinical, gene expression, genomic and epigenetic data in order to elucidate the molecular pathogenesis of PTSD. Over the years, we have built up a number of relatively large samples of participants who have been exposed to traumatic events. This recruitment is ongoing. Animal models of PTSD and other anxiety disorders also form an important basis to our work. Here, we collaborate closely with researchers from the Division of Medical Physiology (Stellenbosch University), Human Biology (Prof Vivienne Russell, University of Cape Town) and Prof Willie Daniels (University of KwaZulu-Natal). The data generated by our group, and many others around the world, looks promising, and may eventually allow us to create a profile of biological markers that can aid diagnosis and treatment of the disorder.



Obsessive-compulsive disorder (OCD) refers to a wide spectrum of repetitive thoughts and actions. Examples of the most frequent obsessions include contamination fears, pathological doubt and need for symmetry, whilst the most frequent compulsions include washing, sweeping, cleaning, checking locks on doors and praying.

2-3% of the population is affected with OCD. Although the exact cause of the disorder is presently unknown, a large body of evidence exists to indicate that both certain neurotransmitter systems (including the serotonergic and dopaminergic neurotransmitter systems) are involved in the development of the disorder. An underlying genetic component has also been implicated in the aetiology of the disorder, and investigating exactly which genetic components are involved is presently a very active research focus worldwide and in our laboratory. Although research into the field psychiatric genetics is still in infancy exciting preliminary results, which have been published in peer-reviewed journals, have been obtained by our group. This data generated by our group, and many others around the world, looks promising, and may eventually allow us to create a profile of biological markers that can aid diagnosis and treatment of the disorder.