The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the reference book used by psychologists to diagnose and categorise the various mental disorders that exist. As research advances new categories and types of disorder, along with different diagnostic criteria, are often formed. The fifth edition of the DSM, released in 2013, included a new category of disorders called obsessive-compulsive and related disorders (OCRDs). These disorders are all thought to be related to obsessive compulsive disorder in some way but are less well know and understood.
This review looks at each of these different disorders and evaluates the usefulness of their new categorisation, as well as looking at potential treatments for OCD and related disorders.
OCD is defined as the presence of obsessions, or repeated intrusive thoughts which cause severe distress, and compulsions, which are behaviours designed to reduce or eliminate the obsession. A typical example could be obsessive worries about locking the front door when you leave the house, and a resulting compulsion would be having to check the door dozens of times before you feel safe leaving the house. These compulsions are often nonsensical or highly disproportionate to reality, and can cause real disruption to a person’s life.
OCD sufferers may also display avoidance, which is behaviour designed to stop them encountering situations likely to provoke obsessive thoughts. Someone with obsessive thoughts about catching infections from physical contact with other people, for example, may go to great lengths to avoid physical contact so as not to have to perform the resulting compulsions.
OCD Diagnosis Issues
OCD can currently be diagnosed under the DSM 5 based on the presence of either obsessions or compulsions. This does not reflect the fact that obsessions and compulsions have to be linked- the compulsion is specifically done in order to suppress the obsession.
In earlier version of the DMS, OCD was categorised as an anxiety disorder alongside such disorders as phobias, panic disorder and PTSD. This makes sense because the symptoms of OCD often appear very similar to those of other anxiety disorders, and both the underlying mechanisms and treatment for OCD share many similarities with anxiety treatment.
Under the new categorisation, OCD is grouped with disorders which share features relating to compulsive behaviour and failures of inhibition. There is some debate as to whether it is correct to categorize OCD in such a way.
Obsessive Compulsive Related Disorders
The category of Obsessive Compulsive Related Disorders includes the following conditions:
Trichotillomania (hair pulling)
Trichotillomania is defined as recurrent hair pulling resulting in hair loss combined with attempts to stop doing so. This compulsive hair pulling may appear somewhat similar to the behaviours associated with OCD but is driven by a different process: trichotillomania does not stem from the need to suppress recurrent fearful thoughts but from general feelings of anger, tension, depression or frustration. Whereas compulsions in OCD contain no aspect of enjoyment, those suffering from trichotillomania do gain some satisfaction or pleasure from their hair-pulling behaviour.
Similar to trichotillomania, skin picking is defined as obsessive picking or scratching despite efforts to stop doing so. The mechanisms behind the two disorders are similar: both stem from a sense of anger, anxiety or frustration rather than a need to suppression an obsessive worry, as is the case with OCD.
Hoarding disorder is defined as an excessive need to acquire possessions and a high reluctance to part with them, even those possessions of limited value, for fear that they may one day be needed. Patients with hoarding disorder often live in extremely cluttered houses, to the extent that normal life may become difficult. Until recently hoarding was considered a symptom for OCD, but the thoughts behind the desire to hoard are distinct from the obsessive thoughts present in OCD. Hoarding is not undertaken to alleviate fearful thoughts, and does not suppress the intrusive desire to collect and hold onto possessions, and so cannot be considered a compulsion.
Body Dysmorphic Disorder
BDD is defined as an intense preoccupation with perceived flaws in your appearance which are barely noticeable to other people, as well as repetitive behaviours and thoughts in response. These repetitive behaviours may be things like constantly checking your appearance in the mirror or mentally comparing yourself to others. The symptoms of BDD overlap with those of OCD in that the recurring thoughts about appearance are intrusive and anxiety-provoking in the same way that obsessive thoughts are in OCD. The resulting behaviours serve to maintain the cycle of thoughts and actions in the same way that the compulsions do for OCD patients.
These disorders all share a superficial similarity in that they all involve some form of repetitive behaviour, but the underlying motivations behind these behaviours are often quite different. One interesting difference is that the behaviours OCD and BDD are designed to reduce a feeling of anxiety, whereas in skin picking and hair pulling disorders the repetitive behaviour produces positive emotions, such as a rush of excitement or satisfaction.
Age of Onset
All of the OCRDs display similarities in their age of onset and subsequent course in that all of them are most commonly diagnosed in adolescence and early adulthood and then persist for many years, often with rises and falls in severity. Since many disorders share similarities in terms of onset and trajectory, this on its own cannot be considered a viable reason to group these disorders together.
Another reason that grouping the OCRDs together may be problematic is that they rarely occur together. OCD does, in fact, occur much more commonly alongside other anxiety disorders than it does with hoarding disorder or BDD. Similarly, rates of OCRDs being shared among close family members are much lower than rates of shared anxiety disorders, suggesting they may not be closely linked on a genetic or environmental level.
Treatment of OCD and Related Disorders
One of the key questions when evaluating whether OCRDs should be considered a distinct group of disorders is whether they respond to treatment in the same way.
A category of medication known as SSRIs is considered an effective treatment for OCD. While BDD shows a similar response to these drugs, skin picking and trichotillomania do not- SSRIs produce no better results than a placebo medication for these conditions. SSRIs are also effective treatments for a number of other disorders, including depression and social anxiety. It is therefore not logical to group these disorders together based solely on the idea that their treatment is the same.
Although the disorders belonging to the new category of OCRDs share some superficial similarity, current research suggests they are not linked on any deeper level and grouping them together may not be beneficial. With the exception of BDD, which shares many similarities with OCD, the other disorders in this category bear little resemblance in terms of the causes, thought processes and treatment types involved.
Thinking about OCD purely in terms of repetitive behaviours, as it is categorised currently, undermines the importance of treating OCD by extinguishing the irrational fear that drives obsessive thoughts. Treatment for OCD based on exposure under and anxiety framework has been highly effective but this method of treatment seems unlikely to work for the other disorders in the OCRD category, suggesting new categorisation is required.