What is the Tripartite Model of Anxiety and Depression?


Watson and Clark (1991) proposed the Tripartite Model of Anxiety and Depression to help explain the comorbidity between anxious and depressive symptoms and disorders.

This model divides the symptoms of anxiety and depression into three groups: negative affect, positive affect and physiological hyperarousal. These three sets of symptoms help explain common and distinct aspects of depression and anxiety.

The ability to distinguish between anxiety and depression with this model may help increase diagnostic accuracy and help eliminate the complications that occur with comorbidity. According to Clark, depressed patients have a comorbidity rate of 57% for any anxiety disorder. Other studies in youth have revealed comorbidity rates of anxiety and depression as high as 70%. There are many negative effects of anxiety-depression comorbidity. The negative effects of comorbidity include: chronicity, recovery and relapse rates, and higher suicide risk. Among youth samples, negative effects of anxiety-depression comorbidity include: increased substance abuse, more likely to attempt suicide, receive a diagnosis of conduct disorder, and are less likely to show favourable gains from treatment.


Negative Affect

Negative affect is the factor that is common to both anxiety and depression. Negative affect can be defined as, “the extent to which an individual feels upset or unpleasantly engaged, rather than peaceful”. It involves negative mood states such as subjective distress, fear, disgust, scorn, and hostility. Mood states that are specific to depression include sadness and loneliness that have large factor loadings on negative affect. Some common symptoms of negative affect include: insomnia, restlessness, irritability, and poor concentration.

There is a substantial amount of empirical research on negative affect (NA) and its role in the tripartite model. For example, the Mood and Anxiety Symptom Questionnaire (MASQ) was administered to a sample of college students and a sample of psychiatric patients. The correlations between the specific anxiety scale (anxious arousal) in the MASQ and NA were moderate (rs= .41 and .47), supporting that NA is specific to anxiety disorders, congruent with the tripartite model. Another study consisted of a sample of children (ages 7-14) diagnosed with a principal anxiety disorder. The children completed the Positive and Negative Affect Scale for Children (PANAS-C). The results showed NA was significantly associated with measure of anxiety and depression. A study by Chorpita in 2002, was consistent with the tripartite model. In a large sample of school-aged children, NA was positively correlated with all anxiety and depression scales.

Physiological Hyperarousal

Physiological hyperarousal is defined by increased activity in the sympathetic nervous system, in response to threat. Physiological hyperarousal is unique to anxiety disorders. Some symptoms of physiological hyperarousal include: shortness of breath, feeling dizzy or lightheaded, dry mouth, trembling or shaking, and sweaty palms.

Compared to negative affect and positive affect, physiological hyperarousal has been studied less. Chorpita et al. (2000), proposed an affect and arousal scale in order to measure the tripartite factors of emotion in children and adolescents. In this study, physiological hyperarousal was positively correlated with negative affect but not positive affect. This supports the tripartite model hypothesis, that physiological hyperarousal will distinguish anxiety from depression, which is related to positive affect. Another study by Joiner et al. (1999), analysed the construct validity of physiological hyperarousal. Data were collected from samples of psychotherapy outpatients, air force cadets, and undergraduate students. Confirmatory factor analyses showed that psychological hyperarousal is a reliable, replicable, valid, and discriminable construct.

Positive Affect

Positive affect is a dimension that reflects one’s level of pleasurable engagement with their environment. High positive affect is made up of enthusiasm, energy level, mental alertness, interest, joy, social dominance, adventurousness, and activeness. In contrast, a low level of positive affect, or absence of, is called anhedonia. Anhedonia is described as the loss of interest or the inability to experience pleasure when experiencing things that used to be pleasurable. Low levels of positive affect in the Tripartite Model characterise depression. Signs of low positive affect include fatigue, loneliness, sadness, and lethargy. Positive affect is important because it is a construct used in order to differentiate depression from anxiety.

Many studies were completed to evaluate the role of positive affect in the tripartite model. A sample of university students were administered the Positive and Negative Affective Schedule (PANAS), the Beck Depression Inventory (BDI), and the Beck Anxiety Inventory (BAI). The results of this study were congruent with low Positive Affect predicting depression. A longitudinal study was completed with a sample of students in grade 6 and later grade 9. The students completed the Baltimore How I Feel (BHIF), a measure of anxious and depressive symptoms. This study confirmed the PA aspect of the tripartite model. A study with a sample of inpatient children/adolescents was consistent with the tripartite model as well. Findings from a study in 2006 of a community sample of youth supported the tripartite in youth and further supported that anxiety and depression do represent unique syndromes in youth based on differences found in positive affect. Many studies looked at samples of youth but studies were also done with older adult samples. A study consisting of psychiatric outpatients, ages 55-87, confirmed that positive affect was significantly more related to depression than anxiety symptoms.



The Positive and Negative Affect Schedule (PANAS) was developed by Watson, Clark, and Tellegen in 1988. This scale is brief, easy to administer, and is used to measure positive affect and negative affect. The scale uses 20 adjectives that describe different moods ranging from excited to upset. There are 10 positive affect adjectives and 10 negative affect adjectives. Individuals are asked to rate each adjective on a 5-point scale (1 – very slightly or not at all to 5 – extremely) based on how they feel. The time frame in which they make these ratings varies based on the study.


Watson and Clark established the 90-item Mood and Anxiety Symptom Questionnaire (MASQ). The MASQ consists of five subscales that measure: mixed general distress symptoms (GD: Mixed, 15 items), general distress depressive symptoms (GD: Depression, 12 items), general distress anxiety symptoms (GD: Anxiety, 11 items), anxious arousal symptoms (Anxious Arousal, 17 items) and anhedonic depression symptoms (Anhedonic Depression, 22 items). All individual items are rated on a scale 1 to 5, where 1 (not at all) indicates the individual has not felt this way at all during the past week and 5 (extremely) indicates that they have felt this way extremely.

Can the MHS: A Serve as a Clinically Useful Screening Tool for GAD?

Research Paper Title

A Brief Online and Offline (Paper-and-Pencil) Screening Tool for Generalized Anxiety Disorder: The Final Phase in the Development and Validation of the Mental Health Screening Tool for Anxiety Disorders (MHS: A).


Generalised anxiety disorder (GAD) can cause significant socioeconomic burden and daily life dysfunction; hence, therapeutic intervention through early detection is important.


This study was the final stage of a 3-year anxiety screening tool development project that evaluated the psychometric properties and diagnostic screening utility of the Mental Health Screening Tool for Anxiety Disorders (MHS: A), which measures GAD.


A total of 527 Koreans completed online and offline (i.e., paper-and pencil) versions of the MHS: A, Beck Anxiety Inventory (BAI), Generalised Anxiety Disorder-7 (GAD-7), and Penn State Worry Questionnaire (PSWQ). The participants had an average age of 38.6 years and included 340 (64.5%) females. Participants were also administered the Mini-International Neuropsychiatric Interview (MINI).

Internal consistency, convergent/criterion validity, item characteristics, and test information were assessed based on the item response theory (IRT), and a factor analysis and cut-off score analyses were conducted. The MHS: A had good internal consistency and good convergent validity with other anxiety scales.

The two versions (online/offline) of the MHS: A were nearly identical (r = 0.908). It had a one-factor structure and showed better diagnostic accuracy (online/offline: sensitivity = 0.98/0.90, specificity = 0.80/0.83) for GAD detection than the GAD-7 and BAI. The IRT analysis indicated that the MHS: A was most informative as a screening tool for GAD.


The MHS: A can serve as a clinically useful screening tool for GAD in Korea. Furthermore, it can be administered both online and offline and can be flexibly used as a brief mental health screener, especially with the current rise in telehealth.


Kim, S-H., Park, K., Yoon, S., Choi, Y., Lee, S-H. & Choi, K-H. (2021) A Brief Online and Offline (Paper-and-Pencil) Screening Tool for Generalized Anxiety Disorder: The Final Phase in the Development and Validation of the Mental Health Screening Tool for Anxiety Disorders (MHS: A). Frontiers in Psychology. doi: 10.3389/fpsyg.2021.639366. eCollection 2021.

What is the Beck Anxiety Inventory?


The Beck Anxiety Inventory (BAI), created by Aaron T. Beck and other colleagues, is a 21-question multiple-choice self-report inventory that is used for measuring the severity of anxiety in children and adults. The questions used in this measure ask about common symptoms of anxiety that the subject has had during the past week (including the day you take it) (such as numbness and tingling, sweating not due to heat, and fear of the worst happening). It is designed for individuals who are of 17 years of age or older and takes 5 to 10 minutes to complete. Several studies have found the Beck Anxiety Inventory to be an accurate measure of anxiety symptoms in children and adults.

The BAI contains 21 questions, each answer being scored on a scale value of 0 (not at all) to 3 (severely). Higher total scores indicate more severe anxiety symptoms. The standardised cutoffs are:

  • 0-7: Minimal.
  • 8-15: Mild.
  • 16-25: Moderate.
  • 26-63: Severe.

The BAI has been criticised for its predominant focus on physical symptoms of anxiety (most akin to a panic response). As such, it is often paired with the Penn State Worry Questionnaire, which provides a more accurate assessment of the cognitive components of anxiety (i.e. worry, catastrophising, etc.) commonly seen in generalised anxiety disorder.

Two Factor Approach to Anxiety

Though anxiety can be thought of as having several components, including cognitive, somatic, affective, and behavioural components, Beck et al. included only two components in the BAI’s original proposal: cognitive and somatic. The cognitive subscale provides a measure of fearful thoughts and impaired cognitive functioning, and the somatic subscale measures the symptoms of physiological arousal.

Since the introduction of the BAI, other factor structures have been implemented, including a four factor structure used by Beck and Steer with anxious outpatients that included neurophysiological, autonomic symptoms, subjective, and panic components of anxiety. In 1993, Beck, Steer, and Beck used a three factor structure including subjective, somatic, and panic subscale scores to differentiate among a sample of clinically anxious outpatients.

Because the somatic subscale is emphasized on the BAI, with 15 out of 21 items measuring physiological symptoms, perhaps the cognitive, affective, and behavioural components of anxiety are being deemphasized. Therefore, the BAI functions more adequately in anxiety disorders with a high somatic component, such as panic disorder. On the other hand, the BAI will not function as adequately for disorders such as social phobia or obsessive-compulsive disorder, which have a stronger cognitive or behavioural component.

Clinical Use

The BAI was specifically designed as “an inventory for measuring clinical anxiety” that minimizes the overlap between depression and anxiety scales. While several studies have shown that anxiety measures, including the State-Trait Anxiety Inventory (STAI), are either highly correlated or indistinguishable from depression, the BAI is shown to be less contaminated by depressive content.

Since the BAI does only questions symptoms occurring over the last week, it is not a measure of trait anxiety or state anxiety. The BAI can be described as a measure of “prolonged state anxiety”, which, in a clinical setting, is an important assessment. A version of the BAI, the Beck Anxiety Inventory-Trait (BAIT), was developed in 2008 to assess trait anxiety rather than immediate or prolonged state anxiety, much like the STAI. However, unlike the STAI, the BAIT was developed to minimize the overlap between anxiety and depression.

A 1999 review found that the BAI was the third most used research measure of anxiety, behind the STAI and the Fear Survey Schedule, which provides quantitative information about how clients react to possible sources of maladaptive emotional reactions.

The BAI has been used in a variety of different patient groups, including adolescents. Though support exists for using the BAI with high-school students and psychiatric inpatient samples of ages 14 to 18 years, the recently developed diagnostic tool, Beck Youth Inventories, Second Edition, contains an anxiety inventory of 20 questions specifically designed for children and adolescents ages 7 to 18 years old.


Though the BAI was developed to minimise its overlap with the depression scale as measured by the Beck Depression Inventory, a correlation of r=.66 (p<.01) between the BAI and BDI-II was seen among psychiatric outpatients, suggesting that the BAI and the BDI-II equally discriminate between anxiety and depression.

Another study indicates that, in primary care patients with different anxiety disorders including social phobia, panic disorder, panic disorder with or without agoraphobia, agoraphobia, or generalised anxiety disorder, the BAI seemed to measure the severity of depression. This suggests that perhaps the BAI cannot adequately differentiate between depression and anxiety in a primary care population.

In a study examining the BAI’s use on older adults with generalised anxiety disorder, no discriminant validity was seen between the BAI and measures of depression. This could perhaps be due to the increased difficulty in discriminating between anxiety and depression in older adults due to “de-differentiation” of the symptoms of anxiety with the aging process, as hypothesized by Krasucki et al.

Many questions of the Beck Anxiety Inventory include physiological symptoms, such as palpitations, indigestion, and trouble breathing. Because of this, it has been shown to elevate anxiety measures in those with physical illnesses like postural orthostatic tachycardia syndrome, when the Anxiety Sensitivity Index did not.

Finally, the mean and median reliability estimates of the BAI tend to be lower when given to a nonpsychiatric population, such as college students, than when given to a psychiatric population.

Refer to Beck Depression Inventory, Beck Hopelessness Scale, Major Depression Inventory, and Quality of Life in Depression Scale.