Does Generalized Anxiety Disorder Exist?
Vol 3 #4
Alan Eppel MB, FRCPC
“The diagnosis of generalised anxiety disorder is a distraction of no value. It is highly unreliable, co-occuring with many other disorders of firmer diagnostic status……..classification would be heartily relieved to rid itself of this unnecessary appendage and for the symptom of anxiety to remain as a descriptive term only.”
RECENT HISTORY OF THE ANXIETY CONSTRUCT
The term anxiety neurosis was first used by Freud in 1895 n German “angstneurose” and in French “nervrose d’angoisse”.
The first DSM was released in 1952 and in 1968 DSM-II was published. In DSM II the diagnostic category “anxiety neurosis” was characterized by “anxious over-concern extending to panic and frequently associated with somatic symptoms” which includes both of what is now called panic attacks and GAD.
In 1980 in DSM-III, the concept of anxiety neurosis was split in two: generalized anxiety disorder and panic disorder. This split was supported by Klein’s “pharmacological dissection”. Klein demonstrated that panic disorder responded to imipramine whereas generalized anxiety disorder responded to benzodiazepines. This differentiation did not hold up over time and both classes of drugs can be effective for each condition.
More recently authors have felt that GAD is a residual category because individuals diagnosed with other anxiety disorders appear to meet the criteria for GAD simultaneously.
Up until DSM-III there was a hierarchical approach whereby a diagnosis of depression preempted a diagnosis of anxiety. This makes clinical sense and that depression may take precedence and treatment priorities.
The high rate of comorbidity of GAD and major depression is also problematic. It has been argued that GAD and MDD are both manifestations of the same condition. Alternatively GAD may be a prodrome to depression or represent a severity marker.
Approximately 85% of patients with depression also have significant anxiety symptoms. Conversely 90% of patients with anxiety disorders have depressive symptoms.
This raises questions as to the therapeutic usefulness of maintaining these as separate diagnoses.
DSM incorporated a hierarchical view: if a patient met criteria for depression then anxiety disorders were excluded as a diagnosis. This ensured focus on the superordinate diagnosis.
DSM-5 defines generalized anxiety disorder as excessive anxiety and worry. Worry is described as apprehensive expectation emphasizing that it is future orientated. This is in contrast to rumination which refers to thoughts about past events.
Three of six symptoms are also required for the diagnosis: feeling keyed up or on edge; restlessness; being easily fatigued; difficulty concentrating; irritability; muscle tension and sleep disturbance.
In DSM 5 it is noted that general anxiety or worry is a common feature of depressive, bipolar and psychotic disorders and should not be diagnosed separately if the excessive worry has occurred only during the course of these conditions.
In DSM-5, GAD is largely a diagnosis of exclusion. GAD cannot be diagnosed if the anxiety is better explained by another anxiety disorder (panic, phobic, social anxiety, or obsessive-compulsive disorder). Also, GAD cannot be caused directly by stressors or trauma, contrary to adjustment disorders and PTSD
Major depressive disorder is characterized by depressed mood, anhedonia, insomnia psychomotor agitation or retardation, fatigue, feelings of worthlessness/guilt difficulty in concentration thoughts of death or suicide.
Depression can have a specifier of “anxious distress”:
feeling keyed up or tense; feeling restless; difficulty concentrating because of worry; fear the something awful may happen; fear of losing control.
SIMILAR SYMPTOMS IN DEPRESSION, GAD AND PTSD
- depressed mood
- loss of interest
- loss of pleasure
- loss of energy fatigue
- agitation feelings of worthlessness guilt
- decreased concentraion
- suicidal ideation
- excessive anxiety and worry (apprehensive expectation),
- restlessness, feeling keyed up or on edge.
- difficulty concentrating or mind going blank.
- muscle tension.
- sleep disturbance.
Criteria D DSM 5
- persistent negative cognitions and mood
- negative beliefs or expectations about self, others, the world
- self blame for traumatic event
- negative emotional states fear, horror, anger, guilt, shame
- diminshed interest in activities
- persistent inability to experience positive emotions, happiness, satisfaction, loving feelings,
- problems with concentration
- sleep disturbance
TRANSDIAGNOSTICS: FROM DSM TO RDOC
Sharp et al. identify the crux of the problem with the DSM approach:
” …the inability to differentiate between identical symptom presentations that are caused by two different etiologies…”.
Anxious Apprehension and Anxious Arousal are two distinct dimensions of anxiety.
Anxious apprehension is the propensity to engage in negative repetitive thinking (worry).
Anxious arousal is an enduring pattern of hypervigilance, sympathetic arousal and fear.
These constructs are:
- dimensional not categorical
- continuous with normal population
- have specific correlates with neurobiological measures
- can be measured by self report
- distinct from anhedonia.
- correlated with fMRI and EEG measurements
In contrast to the trans-diagnostic anxiety dimensions, anhedonia is a separate dimension that is associated with the diagnosis of depression and has distinct neuroimaging correlates.
Current categorical diagnoses are limited by reliance on overlapping criteria that lead to artificial “co-morbidities”. The GAD construct is a prime illustrative example of this.
Dimensional approaches allow for identification of early and less severe illness presentations that could lead to preventative interventions. This is consistent with other areas of medicine eg hypertension and hypercholesterolemia are examples of dimensional diagnoses that allow for early intervention and secondary prevention.
REFERENCES AND ABSTRACTS
Brown TA.The nature of generalized anxiety disorder and pathological worry: current evidence and conceptual models. Can J Psychiatry. 1997 Oct;42(8):817-25.
Many important questions remain regarding the validity of current conceptual models of pathological worry and the discriminability of GAD from certain emotional disorders (for instance, mood disorders) and higher-order trait vulnerability dimensions (for example, negative affect).
Because the features of GAD are salient to current conceptual models of emotional disorders (for example, models that implicate negative affect or worry/anxious apprehension as vulnerability factors), research on the nature of GAD and its associated features should provide importantinformation on the pathogenesis, course, and co-occurrence of the entire range of anxiety and mood disorders.
Castagna PJ, Roye S, Calamia M, et al. Parsing the neural correlates of anxious apprehension and anxious arousal in the grey-matter of healthy youth. Brain Imaging Behav. 2017 Oct 9.
Neuroscientific and psychological research posits that there are two
transdiagnostic facets of anxiety: anxious arousal and anxious apprehension. Though these two facets of anxiety are distinct, they are often subsumed into one domain (e.g., trait anxiety).
Results of this study indicated that the right anterior insula has a stronger
relationship to anxious arousal, whereas the dorsolateral prefrontal cortex and left anterior insula were found to correlate with both anxious arousal and
apprehension. The authors found volumetric differences in the amygdala and hippocampus between anxious arousal and anxious apprehension. Anxious arousal predicted left amygdala volume, anxious apprehension,predicted right hippocampal volume. These findings demonstrated that there are both differences and similarities in the neural regions that contribute to independent facets of anxiety.
Coutinho FC, Dias GP, do Nascimento Bevilaqua MC, Gardino PF, Pimentel Rangé B, Nardi AE. Current concept of anxiety: implications from Darwin to the DSM-V for the diagnosis of generalized anxiety disorder. Expert Rev Neurother. 2010 Aug;10(8):1307-20.
This article proposes a revision of the historical evolution of the concepts of generalized anxiety disorder (GAD). Currently, Darwin’s evolutionary theory is the dominant paradigm for modern science and influences research on mental disorders.
The successive editions of the Diagnostic and Statistical Manual of Mental Disorders have revised the diagnostic criteria for GAD, reflecting the prevailing psychiatric understanding of this disorder. The prevalence and symptoms of major depression and GAD show the fragility of the categorical conception of these conditions. Differences in cultural views towards anxiety disorders also suggest that anxiety cannot have a uniform definition. This article provides contributions for reflecting future guidelines concerning the diagnostic criteria for GAD in DSM-V.
Crocq M. The history of generalized anxiety disorder as a diagnostic category. Dialogues Clin Neurosci. 2017 Jun; 19(2): 107–116.
Sharp PB, Miller GA, Heller W. Transdiagnostic dimensions of anxiety: Neural mechanisms, executive functions, and new directions. Int J Psychophysiol. 2015 Nov;98(2 Pt 2):365-377.
doi: 10.1016/j.ijpsycho.2015.07.001. Epub 2015 Jul 5.
Neuroscientific and psychological evidence points to severaltransdiagnostic factors that cut across DSM-defined disorders, which both affect and are affected by executive dysfunction. Two factors, anxiousapprehension and anxious arousal, have helped bridge the gap between psychological and neurobiological models of anxiety. This article integrates diverse findings of the relationships between these transdiagnostic anxiety dimensions, their interactions with each other and executive function, and their neural mechanisms.
The authors discuss how these constructs fit within the Research Domain Criteria (RDoC) matrix developed by the National Institutes of Mental Health and how they relate to other anxiety constructs studied with different methods and at other units of analysis.
Somerville LH, Whalen PJ, Kelley WM. Human bed nucleus of the stria terminalis indexes hypervigilant threat monitoring. Biol Psychiatry. 2010 Sep 1;68(5):416-24.
A key symptom underlying many anxiety disorders is hypervigilant threat monitoring. Animal models suggest that anxious processes such as hypervigilant threat monitoring are distinct from cued fear-like responses and mediated by the bed nucleus of the stria terminalis (BNST).
In this study healthy participants (n = 50) with varying trait anxiety performed an environmental threat-monitoring task during functional magnetic resonance imaging where a stimulus line continuously fluctuated in height, providing information relevant to subsequent risk for electric shocks. Skin conductance was collected in a separate cohort (n = 47) to validate task-evoked modulation of physiological arousal.
The results of this study demonstrated that the BNST and insula continuously monitored changes in environmental threat level and also subserved hypervigilant threat-monitoring processes in more highly trait anxious individuals. These findings bridge human and animal research informing the role of the BNST in anxious-related processes.
These findings suggest that continuous functional magnetic resonanceimaging paradigms offer promise in further elucidating the neural circuitries supporting sustained anticipatory features of anxiety.
Tyrer P. Against the stream: Generalised anxiety disorder (GAD)- a redundant diagnosis.BJPsych Bulletin 2018, 69-71.
Watson D. Rethinking the mood and anxiety disorders: a quantitative hierarchical model for DSM-V. J Abnorm Psychol. 2005 Nov;114(4):522-36.