Clark And Watson’s Tripartite Anxiety-depression Model

Anxiety and depression are two diagnostic categories that attempt to differentiate between two different psychological disorders. On the one hand, anxiety is conceptualized as a tendency to apprehension, an alarm for some future danger and a high physiological activation, among other issues that depend more on the specific disorder. Depression, in turn, is mainly characterized by a markedly low mood, associated with a series of symptoms that, in general, occur or compete with it: lack of appetite, anhedonia, apathy, insomnia, etc.

Although it seems that the two concepts are exclusive, the truth is that in everyday clinical practice, we can easily see that they tend to go together. Although the DSM-5 has not yet created a diagnostic category that brings together the symptoms of both, the ICD-10 includes as its own category the diagnosis of mixed depressive-anxiety disorder.

According to the WHO, the diagnostic category that we have just defined is frequent in primary medicine, and even more so in the non-clinical population (people who do not require therapeutic care).

In 1991 authors Clark and Watson proposed a “tripartite model of anxiety-depression.” As established, the model is composed of three elements named: negative affect or anxiety, physiological hyperarousal and anhedonia or decrease in positive affect. Clark and Watson suggest that the presence of high levels of negative affect is a common indicator of anxiety and depressive disorders.

Subtypes of depressive anxiety disorders according to the tripartite model

According to Clark and Watson, there are two subtypes of disorders in the anxiety-depression category. Patients whose predominant symptoms are nonspecific (anguish, irritability, loss of appetite, sleep disturbances, vague somatic complaints, etc.) and show moderate levels of both specific factors should be diagnosed as  mixed anxiety-depression disorder. This would be a similar category to the ICD-10 proposal that we discussed earlier.

On the other hand, when patients report very high levels, not only in negative affect, but also in  anhedonia and psychophysiological hyperactivity, they should be diagnosed as severe anxiety-depression disorder.

Positive affect and negative affect

Clark and Watson’s tripartite model is based on the concept of positive and negative affect. With the PANAS questionnaire, developed by the same research group, we can assess both dimensions. Positive affect would be anything contrary to sadness, anhedonia or apathy, for example. On the other hand, negative affect – common in both dimensions – would range from irritability to guilt or feelings of inferiority.

For the authors, anxiety and depression share many symptoms of emotional distress. But it is also true that other patients who suffer from depressive symptoms do not manifest anxiety symptoms and vice versa. The tripartite anxiety-depression model postulated by these authors indicates that what characterizes and differentiates the depressed patient from the anxiety patient is precisely the low positive affect. 

The tripartite model of anxiety-depression

According to the tripartite model, on the one hand  we would have the dimension of depression, which would have a series of its own characteristics. These would be as follows: First, we would find low positive affect and hopelessness. In addition, there would be symptoms such as sadness, anhedonia, apathy, suicidal tendencies, low sympathetic activation, loss of appetite, psychomotor inhibition, feeling of uselessness and perception of loss.

In turn, anxiety would include physiological hyperarousal and uncertainty as the main elements. Other symptoms proposed by the tripartite model for anxiety would be fear, panic, nervousness, avoidance, instability, high sympathetic activation, muscle tension, hypervigilance, threat/danger perception.

The model also includes a series of symptoms common to both pathologies. Negative affect, as we have already pointed out, is in the foreground in this case. But helplessness also plays an important role in bringing together anxiety and depression. Other common symptoms we encounter are irritability, worry, poor concentration, insomnia, fatigue, psychomotor agitation, crying, feelings of inferiority, guilt and low self-esteem.

The authors also note that high negative affect, while common to anxiety and depression, tends to be more characteristic of anxiety. Impotence, while also a common component, is more typical of depression.

Conclusions on the tripartite model

The tripartite model of anxiety-depression opens the door to transdiagnostic treatment. These types of treatments have been gaining increasing relevance in clinical practice, as they have been shown to be effective in treating several diagnoses at the same time or a main diagnosis with its comorbidities. In addition to being effective, they are more efficient in terms of time and financial resources.

From these transdiagnostic approaches, the focus would be on the common nuclei behind both disorders. Following Clark and Watson’s tripartite anxiety-depression model, therapy would have to focus on negative affect and helplessness above all else.