Unveiling the Overlap: Medical Conditions Mimicking Mental Illness from a Therapist's Viewpoint
- Emma Nelson
- Nov 6, 2025
- 3 min read
Thyroid Disorders
Thyroid disorders, especially hypothyroidism and hyperthyroidism, are common culprits affecting mood and mental health. Hypothyroidism may cause symptoms such as depression, fatigue, and cognitive fog, impacting up to 6% of the population. On the other hand, hyperthyroidism can lead to anxiety, irritability, and restlessness, affecting around 1% of individuals.
If left untreated, these conditions can result in misdiagnoses of mood disorders like major depressive disorder or generalized anxiety disorder. It is crucial to test thyroid function when evaluating these symptoms. Early diagnosis can lead to effective treatments, such as hormone replacement therapy or antithyroid medications, which can greatly improve both mood and overall health.

Vitamin Deficiencies
Vitamin deficiencies can play a significant role in mental well-being. For example, vitamin B12 deficiency is known to cause memory loss, confusion, and changes in mood, affecting about 15% of older adults. Similarly, low levels of vitamin D are linked to symptoms of depression, with studies suggesting that almost 80% of individuals with depression have insufficient vitamin D levels.
It is essential for therapists to address these deficiencies, as they are manageable through dietary changes or supplements. A simple blood test can provide insights into vitamin levels, paving the way for a tailored treatment plan that addresses both mood and physical symptoms.
Neurological Disorders
Neurological conditions such as multiple sclerosis (MS) can exhibit psychiatric symptoms. For instance, around 50% of individuals with MS may experience mood swings or depression. These symptoms might lead to misunderstanding and mislabeling of their mental health status.
Therapists must grasp the neurobiological aspects of these conditions to navigate treatment successfully. Early treatment may involve collaborating with neurologists to ensure primary medical issues are managed, which can alleviate both physical and mental health challenges.
Hormonal Imbalances
Hormonal changes, particularly in women, can significantly influence mood. Conditions like premenstrual dysphoric disorder (PMDD) affect approximately 3-8% of women, causing severe emotional distress linked to hormonal fluctuations. Perimenopause and postpartum depression are additional conditions that should prompt evaluation of hormonal factors.
Therapists should carefully consider these hormonal effects before labeling symptoms as solely psychiatric. Working with healthcare providers to initiate hormonal testing can uncover potential sources of distress, ultimately leading to more effective treatment strategies.
Chronic Infections
Chronic infections, such as Lyme disease and syphilis, can manifest psychiatric symptoms. Patients may report anxiety, depression, or cognitive impairments, which can be misattributed to mental health problems. Data suggests that nearly 30% of Lyme disease patients experience psychiatric symptoms, further complicating treatment approaches.
Thoroughly reviewing a patient’s medical history and considering testing for relevant infections can lead to prompt treatment. Addressing these underlying infections can simultaneously alleviate mental health symptoms, showcasing the importance of a multidisciplinary approach.

Final Thoughts
The blending of medical conditions and mental illness is a delicate landscape requiring careful consideration from both healthcare providers and clients. As therapists, we must recognize that symptoms may often arise from underlying medical issues rather than solely from mental health disorders.
Encouraging clients to seek comprehensive evaluations, including medical tests, can bridge gaps where mental health intersects with physical health. By fostering collaboration between mental health and healthcare providers, we can create more tailored treatment plans that enhance clients' overall well-being.
By continuously educating ourselves about the medical conditions that can mimic mental illness, we can adopt a more holistic approach to mental health care. This commitment empowers our clients in their individual journeys towards healing and recovery.



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