2007, Number 2
Salud Mental 2007; 30 (2)
Agudelo D, Buela-Casal G, Donald SC
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ABSTRACTThe differentiation between the symptoms of anxiety and depression is one of the most important problems in psychology as the dilemma profoundly affects the diagnosis and clinical intervention.
According to the epidemiological data there is a strong comorbility between the two types of disorder. Nevertheless, it is not known which one of them precedes or predisposes to the other. The comorbility could be also caused by the confusion between the two. There are many common symptoms and some of them traditionally attributed to the anxiety are also present in depression and vice versa. Additionally, in some cases the symptoms themselves could constitute complete clinical charts.
Taking into account the above description, one of the most important current preoccupations in psychology and psychopathology is the identification of the symptoms which would be characteristic for each disorder. Although there is clinical evidence on an overlap between the symptoms, the current manuals describe two disorders and the clinical differences are crucial.
One of the possible explanations of the overlap between the symptoms of anxiety and depression has been classically attributed to comorbility which means the presence of both charts in many clinical cases. Different sources indicate that the presence of anxiety in early ages can generate certain vulnerability to develop later-age major depression. On the other hand, other studies indicate that the cases in which both, depression and anxiety are present, tend to chronify and are more resistant to treatment. In this case both disorders are present but there is no sufficient evidence to determinate which one of them would be the principal diagnosis and which one would be secondary. For this reason, the explanations are confused and neither the researchers nor clinicians are satisfied.
On the other hand, the concurrence of symptoms has been attributed to the instruments utilized for the evaluation. The disorders also depend on the tools for their measure which follow a theoretical model to explain the aetiology, course, prognosis and associated symptomatology. This way, the implicit bias of the instruments is to privilege a specific aspect which depends on the definition of disorders without taking into account the other aspects.
According the description above, the evaluation, especially in case of depression, is characterized by multiplicity of instruments and diversity of contents which are evaluated. Thus, it is difficult to establish the characteristic symptoms as in many cases only some of them coincide when utilizing different tools. Moreover, many symptoms which are detected by scales of depression are also present in anxiety disorders. This difficulty is one of the most important problems in clinics as it affects the validity and reliability of the tools which assess the disorders.
The importance of the instructions given to the subjects should also be emphasized. In many cases they lead to the confusion of the measures of frequency and severity which is related to the classical discussion about the dimensional or categorical character of depression. Some authors state that the consideration of depression as a dimensional disorder makes possible to understand that some charts, as for example the anxiety disorders, can appear as a consequence of certain vulnerability generated by the depression.
One of the alternatives to explain the presence of symptoms shared by the anxiety and depression is to consider the existence of a factor of negative affect which would be present in both types of disorder. This point of view is derived from the correspondence between some common symptoms in depression and anxiety observed in clinics. Additionally, some items included in the self-report questionnaires and scales are the same for the two disorders. The group of symptoms includes sadness, crying, psychomotor restlessness and irritability among others. The factor which includes these symptoms is called negative affect and would be common for the anxiety and depression.
Although the negative affect factor is the same for anxiety and depression, some elements are characteristic for one disorder but not for the other. In case of anxiety, according to the tripartite model the characteristic factor refers to high physiological activation related to the vegetative symptoms. On the other hand, in depression, the negative affect is also accompanied by low positive affect which can be seen in the lost of interest in things which were enjoyed before (anhedony). Thus, the anxiety would be defined as high negative affect together with high physiological arousal whereas depression is characterized by high negative affect and low positive affect.
For all the reasons described above, the importance of applying adequate and reliable instruments to evaluate the disorders should be emphasized. These instruments would help to clarify the features of each disorder and would support more effective interventions to decrease the rate and incidence of mental disorders in the population. In relation to this, Spielberger et al. offer an instrument which differentiates the aspects characteristic for depression utilizing two different scales: depression as a trait and as a state. The instrument allows the differentiation between the trait and the state which provides the information about the aspects which are more stable and lasting in time related to the mood which probably refer to the personality traits (the trait scale). The aspects which depend more on the punctual moments are measured by the state scale. This is possible thanks to the instructions which evaluate in a different manner the frequency and the severity which are usually confused in most of the sales.
The component of negative affect (Dysthymia) which is common for the anxiety and depression is evaluated together with positive affect (Euthymia) and offers the valuation of low affectation levels which are not considered in most of the self-report questionnaires, although they are crucial for the clinical practice and investigation.