Brain Activity of Bodily Symptoms in Anxiety Disorders

Neuroscience research sheds light on somatic symptoms in anxiety disorders.



Many suffer not only with mental symptoms of anxiety and other mental health conditions, but also physical symptoms, referred to as “somatic” (from the Greek root soma-, meaning “body”).

The Body Speaks

Somatic symptoms include stomach pain; back pain; pain in arms, legs or joints; headaches, chest pain, dizziness, fainting; heart pounding or racing; shortness of breath; sexual problems including pain and performance; bowel irregularity; fatigue and low energy; sleep disturbances; menstrual-related, and others.

Somatic symptoms are common in anxiety, depression, PTSD, bipolar and other psychiatric disorders. Rates of somatic symptoms in clinical samples range from 20 to nearly 50 percent (e.g. Strainge et al, 2019; Edgcomb et al., 2016; Gierk et al., 2017; Gray et al., 2020).

They may be referred to as “medically unexplained symptoms”, also part of normal stress reaction during times of personal crises and disaster. Within psychiatry, somatic symptoms—only when severe and persistent—meet diagnostic criteria, called “Somatoform Disorders.”

Outside of psychiatry, they may be referred to as “functional disorders,” with a specific clinical presentation defying traditional diagnostic categories e.g. Functional Gastrointestinal Disorders (FGD). Psychological issues are more common with functional disorders, for example neuroticism and concealed aggression in FGD. Personality is associated with medically unexplained symptoms e.g in Borderline Personality. Specialists may not recognize or may hesitate to discuss psychological aspects.

The burden of somatic symptoms leads to over-utilization of healthcare, accounting for up to 50 percent of healthcare appointments. They delay diagnosis of other medical disorders as many people learn to live with chronic discomfort, fostering learned helplessness around self-care.

These symptoms add to distress, deplete resources, and in spite of progress are stigmatized and dismissed—e.g. “it’s all in your head.” Quick-fix solutions for anxiety, such as over-prescription of medications like Xanax and Ativan (benzodiazepenes) may interfere with more durable solutions.

Anxiety and Somatic Symptoms In The Brain

The National Institutes of Mental Health (NIMH) reports a yearly rate of anxiety disorders of nearly 20 percent, and lifetime rate over 30 percent. Women are more likely to be diagnosed than men, 23.4 percent versus 14.3 percent. Research shows anxiety disorders are under-diagnosed, often occurring with other conditions, increasing with age. Somatic symptoms are chronic in 20-25 percent of patients.

Given their key role in anxiety and other conditions, it’s important to understand the potential relationship between fear circuits in the brain and medically-unexplained symptoms.

A recent study by Yue Chen, Yue Wu, Jingjing Mu, Bensheng Qiu, Kai Wang and Yanghua Tian in the Journal of Affective Disorders (2020) sheds light on the relationship between anxiety and somatic complaints.

Researchers compared brain scans in 33 patients diagnosed with Generalized Anxiety Disorder (GAD) with a reference group of 25 without diagnoses. The 33 GAD subjects were screened to ensure they did not have other psychiatric conditions.

Participants completed the Hamilton anxiety scale (HAMA), and the Patient Health Questionnaire (PHQ-15), which rates common somatic symptoms.

Resting MRI scans were focused on fear circuits identified in prior research, using ALFF (Amplitude of Low-Frequency Fluctuations) to detect significant findings correlating brain activity with and without somatic symptoms as a function of anxiety severity.

The results showed that ALFF values correlated significantly with higher levels of PHQ-15 and HAMA scores in two key brain regions: the left thalamus and left hippocampus, even after controlling for depression.

The Role of the Hippocampus and Thalamus

The thalamus and hippocampus are both deep brain structures, evolutionarily old and highly conserved across species, part of the basic operating system of the mammalian brain.

The hippocampus is an important brain structure, involved in memory formation, learning, and regulation of important functions related to encoding experiences into patterns of thinking and behavior.

Dysregulated hippocampal function is connected with obsessional thinking, behavioral inhibition, and abnormal consolidation of fear-related memories related to trauma. The hippocampus is thought to be involved in generalization of fear, as abnormal hippocampal function may fail to fence anxiety into specific circumstances.

The thalamus can loosely be thought of as the brain’s “switchboard”, mapping the whole body and relaying information from the body to the brain and back again—including pain nerve signals. The thalamus passes sensory and motor signals, modulating both physical sensation as well as movement.

Symptoms may result from impaired information processing in the thalamus. Weaker signals for the body, for example, may not get gated properly in the thalamus, leading to amplified perception of unpleasant sensations.

While future work is needed to further refine our understanding of how fear circuits and somatic symptoms inter-relate, the hippocampus-thalamus pairing in this study is intriguing.

For instance, somatic symptoms may start as weak signals from the body, in the presence of anxiety and worry, get misinterpreted as being more serious in the absence of appropriate contextualization and inhibition by the hippocampus.

This might happen, for example, with someone sensitized to illness, who fears everyday aches and pains are signs of something dire. Likewise, in pain syndromes with a “central” (meaning central nervous system, or brain) component, pain may be amplified by emotions, and emotional pain may overlap with physical symptoms related to social factors.

The lack of hippocampal modulation of memory and fear could be compounded by thalamic irregularities in processing signals from the body as being stronger than they actually are—compared with what is happening in the body.

The “objective” signal—such as muscle soreness after exercise or a minor injury—may get amplified and misinterpreted as a more severe injury or underlying illness between the hippocampal over-generalization and lack of context—perhaps triggered by runaway post-traumatic responses, and thalamic mis-processing of body signals.

Getting Relief from Somatic Symptoms

While somatic symptoms can be chronic and difficult to resolve, several approaches can be useful for both alleviating symptoms as well as for coping with persistent issues.

Cognitive Behavioral Therapy (CBT), for example, can help shrink anxiety about physical symptoms down to size by properly labeling symptoms for what they are, preventing catastrophizing about worst-case scenarios, and developing adaptive responses such as the use of distraction.

Because pain has a strong subjective component, the way we learn to and choose to cope with pain makes a big difference. This is one of the reasons personality factors like neuroticism and hostility can worsen somatic symptoms, making it harder to let go of excessive worry, reducing insight about the nature of problems, and presenting challenges to accept help from others. Exposure therapy may help with trauma and over-generalization via desensitization, and ultimately reducing somatic triggers.

In addition to CBT, psychodynamic and trauma-informed therapies may help in addressing underlying developmental origins of issues, for example helping to resolve complicated grief related to parental loss or childhood illness which could drive mortality fears, and helping people to learn to articulate and symbolize emotional states and internal conflicts which otherwise would come out as physical symptoms.

Physical exercise and stress-reduction can reduce overall stress, and treatment for underlying conditions such as anxiety and depression are often helpful for relieving associated physical symptoms. Various forms of body work can be useful in re-learning how to process bodily sensations, in addition to directly alleviating discomfort and sometimes for coming to terms with trauma.

Mindfulness-based approaches and meditation, including yoga-based practices, can be useful for alleviating pain. For instance, Mindfulness-Based Interoceptive Exposure Task (MIET) leverages focused awareness of pain dimensions to reduce the impact of pain.

Working on one’s relationship with our bodies can be critically important for addressing somatic symptoms, which may be a reflection of fragmentation in sense of self driven by developmental issues, various forms of mistreatment, bullying and neglect, and habits of distancing oneself from emotional and embodied experience.