Medical Conditions Mimicking Psychiatric Illness
If you’ve been living with unexplained psychological symptoms or going through treatments that don’t seem to help, there may be a piece of the puzzle that hasn’t been looked at yet. But what you may not have considered is that physical illnesses could be the root cause. Many different medical conditions mimic psychological disorders, and they are far more common and consequential than is often realized.
A misdiagnosis isn’t just an incorrect label for what’s going on; it can mean years of ineffective treatment while the underlying physical condition goes unaddressed. Understanding the connection between physical and mental health symptoms can help prevent misdiagnosis and lead to more effective treatment. In this guide, we explore this issue in detail by covering:
- The link between physical illness and mental health symptoms.
- Medical conditions that mimic depression, anxiety, and psychosis.
- The process of ruling out medical causes for mental health.
- How to get an accurate mental health diagnosis and the right treatment.
Hidden Link Between Physical Illness and Mental Health Symptoms
Your brain is an organ like your heart or lungs, and like any organ, it can be affected by disease, hormonal imbalances, and other medical conditions. The effects these conditions have on your brain can look and feel like a psychiatric illness, such as:
Having a physical illness that presents as a psychiatric one can be both frustrating and frightening. Unlike many medical conditions, there isn’t a blood test or lab result that can confirm a psychiatric diagnosis. Instead, mental health providers rely primarily on reported symptoms and clinical observation of behavior.[1]
For these reasons, psychiatric diagnoses can be particularly challenging to make accurately. The subjective component of evaluating psychiatric symptoms makes it easy to mistake the symptoms of a physical illness for a psychological disorder.[2]
When you’re evaluated for a mental disorder, your mental health provider will usually refer to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5 TR) as a guide for making a diagnosis. It includes specific types of disorders, along with detailed diagnostic criteria you must meet for each diagnosis. There’s even a special category in the DSM-5 TR for instances of a medical illness causing psychiatric symptoms: mental disorder due to another medical condition.[2]
Along with the DSM-5 TR’s guidance, your doctor and mental health provider have another means of distinguishing between a medical condition and a psychiatric illness: onset of symptoms. Where the symptoms of a psychiatric illness tend to develop over time, symptoms of an underlying medical condition may appear more abruptly, although this is not always the case.[1]
How Often Does Misdiagnosis Happen?
The DSM-5 TR and differences in symptom onset aren’t guarantees that a proper diagnosis will be made. In fact, research shows nearly 3 percent of adult patients admitted to psychiatric units have symptoms attributable to a medical disorder. Moreover, 2.3 percent of older adults admitted to psychiatric units have a medical disorder that requires intervention within 12 hours.[3]
These percentages may seem small, but for the people they represent, the impact can be life-affecting. It is often measured in years of unanswered questions and ineffective treatment. The obvious immediate effect is that people incorrectly admitted to a psychiatric unit are less likely to receive the proper medical care they need. A delayed diagnosis of the underlying medical condition can then lead to:[3]
- Worsening symptoms.
- Unnecessary psychiatric medication.
- Repeat hospitalizations.
- Increased healthcare costs.
The first step to preventing all of this is knowing which physical conditions are most commonly involved. This is where differential diagnosis in psychiatry becomes essential, as it can help systematically distinguish between medical and psychiatric causes of symptoms.
Medical Conditions That Mimic Depression, Anxiety, and Psychosis
The symptoms associated with many medical conditions can produce psychiatric symptoms as well. And these medical-based symptoms can be extremely convincing, to the point that even experienced clinicians can be misled. The following are some of the most well-documented medical causes of psychiatric symptoms in adults.
Thyroid Issues and Mental Health Symptoms
One of the most common medical conditions that mimics depression is hypothyroidism, or an underactive thyroid. Symptoms include several that are also commonly seen in major depressive disorder:[3][4]
- Fatigue
- Memory problems
- Cognitive slowing
- Low mood
In severe cases, hypothyroidism can even cause psychosis (known as myxedema madness), which includes hallucinations and delusions with no prior history of psychiatric symptoms.[2][4]
Meanwhile, hyperthyroidism, or an overactive thyroid, triggers your body’s fight-or-flight response, which produces a:
- Racing heart.
- Agitation.
- Insomnia.
- Restlessness.
These symptoms closely mimic panic disorder and generalized anxiety disorder. These conditions frequently co-occur, with up to 60% of individuals with hyperthyroidism experiencing significant anxiety.[3]
In some cases, hyperthyroidism can even produce manic and psychotic symptoms, particularly if you have Graves’ disease, an autoimmune disorder in which your immune system attacks the thyroid gland. It’s one of the most common causes of hyperthyroidism.[4]
The link between thyroid function and psychological symptoms is predominantly a chemical one. A thyroid hormone called T3 helps regulate noradrenaline and serotonin, both of which are important neurotransmitters central to mood and can contribute to mood disorders. The good news is that a simple blood test can detect thyroid dysfunction, making it a critically important component of any psychiatric workup.[1]
Beyond hormonal causes, numerous neurological conditions can produce psychiatric symptoms that are just as convincing and can be equally easy to miss.
Neurological Disorders and Mental Health
Some of the most common brain disorders mistaken for mental illness include:
- Parkinson’s disease often causes depression, anxiety, psychosis, and impulse control problems. These symptoms usually appear years before the motor difficulties associated with Parkinson’s.[3]
- Autoimmune encephalitis involves brain inflammation that can produce psychological symptoms like erratic behavior, hallucinations, and paranoia. It’s sometimes misdiagnosed as bipolar disorder or schizophrenia.[1][5] One woman was diagnosed with schizophrenia and treated for 20 years before autoimmune encephalitis was identified as the true cause of her symptoms.[5]
- Moyamoya disease, which causes a progressive narrowing of the brain’s arteries, produces symptoms including depression, psychosis, anxiety, and bipolar-like symptoms.[6]
- Strokes can produce depression and anxiety, and both are extremely common, even after a mild stroke. In some cases, depressive and anxious symptoms appear before other neurological signs.[7]
- Seizure disorders, especially those originating in the temporal lobe, are often misdiagnosed as a psychiatric disorder due to the behavioral and emotional symptoms, such as behavioral changes, impaired or altered consciousness, repetitive and involuntary behaviors, and affective symptoms like intense fear, sadness, or euphoria.[3]
Neurological conditions represent just one category of medical mimics. Hormonal and nutritional disorders can be equally as disruptive.
Other Medical Causes: Adrenal, Autoimmune, and Nutritional
Your body’s adrenal system can produce psychological effects, too. For example, the adrenal glands produce adrenaline and cortisol, both of which drive your body’s stress response. When the adrenal glands malfunction, the hormonal imbalance can disrupt how you think and behave as well as your mood.[3][8]
A related issue, Cushing’s syndrome, is caused by chronically elevated cortisol levels. It can cause symptoms that look and feel like:
- Anxiety.
- Depression.
- Panic disorder.
- Other mood and mental health conditions.
Another adrenal issue, pheochromocytoma, is a physical illness that can cause anxiety symptoms. It involves a tumor of the adrenal gland which causes unpredictable surges in adrenaline, resulting in episodes of sweating, heart palpitations, and intense anxiety.[3]
Adrenal insufficiency (e.g., Addison’s disease) can also cause you to experience psychiatric symptoms. For example, you might experience cognitive impairment, psychosis, depression, and anxiety, sometimes without any accompanying physical symptoms. In fact, up to 60 percent of people with Addison’s disease see at least two clinicians before getting the proper diagnosis.[9] These underlying health conditions and anxiety often go hand in hand, which is why thorough medical evaluation matters.
Nutritional issues are known to create psychological symptoms as well. For example, if you have a Vitamin B12 deficiency, it can contribute to:
- Depression.
- Cognitive decline.
- Irritability.
In extreme cases, it is linked to full psychotic symptoms, including delusions and hallucinations.[10] Another nutritional problem, hypercalcemia (elevated calcium in the blood), can cause you to feel fatigue, depression, and confusion, and in some severe cases, you might experience significant alterations in your mental status.[3]
Given all the ways medical conditions can mimic psychological illnesses, it’s worth understanding not just what those conditions are, but why they often go unrecognized.
Mission Connection is here to help you or your loved one take the next steps towards an improved mental well-being.
Why Mental Health Misdiagnosis Happens
Because there is so much overlap between the symptoms of certain medical conditions and certain psychological issues, even well-intentioned clinicians can misdiagnose you. But that’s not the only issue with misdiagnosis.
Sometimes, cognitive biases can get in the way. For example:[3]
- Premature closure occurs when a mental health professional stops looking for potential causes of the behavior once a plausible explanation is found.
- Diagnostic momentum occurs when a prior psychiatric diagnosis (even an incorrect one) shapes how future symptoms are interpreted.
Both biases make seeing the full picture of what’s actually going on much more difficult.[3]
Another reason why misdiagnoses happen is that psychological symptoms resulting from a medical condition don’t always look like they’re supposed to. They might be inconsistent, atypical, or fragmented, not fitting neatly into the typical diagnostic criteria in the DSM-5 TR.[10] This is why distinguishing mental illness from medical causes requires careful clinical judgment.
Certain populations are at greater risk of misdiagnosis as well. These include:[2]
- People from lower socioeconomic backgrounds.
- Those with existing medical conditions.
- Older adults.
- People without any prior history of a psychiatric disorder.
If you belong to any of these groups, your concerns deserve to be taken seriously. This is why distinguishing mental illness from medical causes requires careful clinical judgment.
Understanding why misdiagnosis happens is a solid step. Knowing what a proper evaluation looks like is the next step.
Ruling Out Medical Causes
When you visit a mental health professional, a thorough medical evaluation is key before getting an accurate mental health diagnosis. Their work at this point in your treatment can mean the difference between simply treating your symptoms and determining and addressing the underlying cause of those symptoms.
Red Flags That Warrant a Medical Workup
As noted earlier, a key red flag that your symptoms are the result of a medical condition is when they appear suddenly or escalate rapidly. Additionally, new psychiatric symptoms when you have no prior psychiatric history are a good indication that an underlying medical issue is at work.[1]
Experiencing any of the following can be unsettling, but recognizing them for what they are is an empowering step in identifying a medical problem as the root of your symptoms:[1][2][11]
- Physical symptoms co-occurring with psychological ones
- Psychological symptoms that don’t respond to standard treatments
- Fluctuating psychological symptoms (e.g., they change in type or intensity from day to day)
- Visual hallucinations
- A discrepancy between reported symptoms and observable daily functioning
Tests and Screenings Clinicians Should Consider
To help minimize the risk of misdiagnosis, a comprehensive medical evaluation should be performed, including a full physical and neurological exam. Moreover, a basic lab screening, including blood count, blood glucose, thyroid and liver function, calcium levels, and vitamin B12 levels, should also be completed.[1][2]
Other tests should complement an initial evaluation as well. A urine drug screen is typical, and an MRI should be done if neurological signs are present. In cases of suspected autoimmune encephalitis, analyzing the cerebrospinal fluid is common, as is autoantibody testing.[1][5]
All this information can feel overwhelming, but it’s more a reason for hope than alarm. With the right approach, it is possible to get an accurate diagnosis and the appropriate care for what you’re experiencing.
Get the Right Diagnosis and the Right Help
If you’ve been experiencing mental health symptoms that you’ve never had before and that aren’t responding well to treatment, it’s worth asking if the cause could be something related to your physical health.[12]
Advocating for yourself is critical. If something about your diagnosis feels off, speak up. If your symptoms change in unexpected ways, tell your health provider. If you have an instinct that you need a second option, act on it.[2] An accurate mental health diagnosis isn’t just a label; it’s the foundation of effective treatment and genuine recovery.
At Mission Connection, our approach is based on the belief that accurate, compassionate care starts with seeing the whole person, not just the symptoms. We’ll take the time to understand your unique situation because you deserve care that gets it right.
We offer flexible outpatient mental health treatment programs that include in-person treatment at our locations, telehealth, and a hybrid approach that combines in-person and virtual care.
Get started online or call us for a free, zero obligation conversation at 866-833-1822. A more accurate, more hopeful path forward may be closer than you think.
