Vitamin B12 deficiency can cause psychiatric symptoms like depression, anxiety, and emotional distress that may be mistaken for primary mental health disorders. According to Gram Research analysis of this case report, a 39-year-old patient was misdiagnosed with anxiety and somatic symptom disorder for nine months before doctors discovered his critically low B12 level (below 37 pmol/L) and spinal cord damage. After receiving B12 treatment, he recovered significantly within five months, becoming fully ambulatory with near-normal psychological scores. The case highlights that when psychiatric symptoms don’t respond to treatment or are accompanied by physical signs like weakness or numbness, doctors must investigate underlying medical causes.
A 39-year-old man spent nine months being treated for anxiety and depression when he actually had a serious vitamin B12 deficiency affecting his spinal cord. According to Gram Research analysis, his case shows how doctors can miss dangerous physical conditions when patients first complain of fatigue, dizziness, and emotional distress. The man’s symptoms got worse until he developed leg weakness and walking problems, which finally led doctors to test his B12 levels. Once he received vitamin B12 treatment, he recovered significantly. This case highlights an important lesson: when someone has both mental health symptoms and physical signs like weak reflexes or numbness, doctors need to check for underlying medical problems before assuming it’s purely psychiatric.
Key Statistics
A 2026 case report published in Frontiers in Psychiatry documented a 39-year-old patient whose vitamin B12 deficiency was initially misdiagnosed as a psychiatric disorder, with a critically low serum B12 level of less than 37 pmol/L and characteristic spinal cord damage visible on MRI.
The misdiagnosed patient showed significant recovery within five months of starting vitamin B12 treatment, achieving full ambulatory status and near-normalization of psychological test scores, demonstrating the importance of investigating physical causes of psychiatric symptoms.
The patient’s psychological testing revealed a high somatization factor of 3.00, indicating numerous reported physical symptoms that actually reflected real nerve damage rather than psychiatric manifestation of distress.
The Quick Take
- What they studied: A single patient whose vitamin B12 deficiency was mistaken for a psychiatric disorder, examining how and why this misdiagnosis happened and what warning signs doctors should have caught.
- Who participated: One 39-year-old male patient who presented with nine months of progressive symptoms including tingling sensations, dizziness, emotional distress, and eventually leg weakness and walking difficulties.
- Key finding: The patient had critically low vitamin B12 levels (below 37 pmol/L) and damage to his spinal cord visible on MRI, but these were only discovered after he was initially misdiagnosed with anxiety and somatic symptom disorder and treated with psychiatric medications.
- What it means for you: If you experience persistent fatigue, numbness, dizziness, and emotional distress that doesn’t improve with psychiatric treatment, ask your doctor to check your vitamin B12 levels. Physical symptoms combined with mental health complaints warrant investigation for underlying medical causes, not just psychiatric treatment alone.
The Research Details
This is a case report, which means doctors documented the medical history and treatment of a single patient in detail. The patient came to the hospital with nine months of worsening symptoms including tingling in his hands and feet, dizziness, and emotional distress. Initial tests like brain CT scans and EEG (which measure brain electrical activity) came back normal, so doctors assumed his problems were psychiatric in nature.
The patient was treated with multiple psychiatric medications, but instead of improving, he got worse. He developed weakness in his legs and problems with balance and coordination. Only when these more obvious physical symptoms appeared did doctors at a specialized medical center perform additional testing. They discovered the patient had extremely low vitamin B12 levels and damage visible on MRI scans in the part of the spinal cord that handles sensation and movement.
After receiving vitamin B12 injections and oral supplements, along with an antidepressant for remaining emotional symptoms, the patient recovered dramatically. At a five-month follow-up, he could walk normally again and his psychological test scores had nearly returned to normal.
This case report is important because it demonstrates a real clinical problem called ‘diagnostic overshadowing’—when doctors focus so much on one diagnosis (in this case, a psychiatric disorder) that they miss a serious underlying physical condition. Vitamin B12 deficiency can cause nerve damage that gets progressively worse if not treated. The longer the condition goes untreated, the more permanent the damage becomes. This case shows that doctors need to stay alert for warning signs that suggest a physical problem rather than a purely psychiatric one.
As a case report of a single patient, this study cannot prove that B12 deficiency always causes psychiatric symptoms or that all similar cases will respond the same way. However, case reports are valuable for identifying patterns and warning signs that doctors should watch for. The strength of this case is that it documents clear objective findings (absent reflexes, spinal cord damage on MRI, critically low B12 levels) alongside the subjective psychiatric symptoms, making a strong argument for the connection. The patient’s dramatic recovery after B12 treatment further supports the diagnosis.
What the Results Show
The patient initially presented with nine months of progressive symptoms: tingling sensations (paresthesia), dizziness, and emotional distress. Because these symptoms are common in psychiatric conditions, he was diagnosed with Somatic Symptom Disorder (a condition where people experience significant physical symptoms without a clear medical cause) and anxiety disorder. He was treated with multiple psychiatric medications, but his condition continued to worsen.
The critical turning point came when the patient developed objective physical signs that couldn’t be attributed to psychiatric illness alone: weakness in his lower limbs and ataxia (loss of coordination and balance). Physical examination revealed absent patellar reflexes (the knee-jerk reflex) and impaired ability to sense vibration—both signs of nerve damage. These findings prompted more thorough testing.
Blood work revealed a critically low serum vitamin B12 level of less than 37 pmol/L (normal is typically 200-900 pmol/L). MRI imaging showed characteristic damage in the dorsal columns of the spinal cord—the nerve pathways responsible for sensation and coordination—extending from the neck (C3) down to the mid-back (T12). This pattern of damage is the hallmark of subacute combined degeneration, a serious neurological condition caused by B12 deficiency.
Following treatment with intramuscular vitamin B12 injections and oral supplements, combined with escitalopram (an antidepressant for residual emotional symptoms), the patient showed remarkable recovery. At five-month follow-up, he was fully ambulatory (able to walk normally) with near-complete normalization of his psychological test scores.
Psychological testing using the SCL-90 scale showed a high somatization factor (3.00), meaning the patient reported many physical symptoms. However, this high score reflected actual nerve damage rather than psychological distress manifesting as physical symptoms. After B12 treatment, these scores normalized, suggesting that the physical symptoms were driving the psychological distress, not the other way around. This finding underscores how physical illness can masquerade as psychiatric illness when doctors don’t look carefully for underlying causes.
This case aligns with established medical literature showing that vitamin B12 deficiency can present with psychiatric symptoms before obvious neurological signs appear. The condition is known to cause fatigue, mood changes, cognitive problems, and emotional distress. However, this case is particularly instructive because it documents the specific sequence of events: psychiatric symptoms first, followed by physical signs, followed by diagnosis and recovery. It demonstrates the real-world problem of ‘diagnostic overshadowing,’ where an initial psychiatric diagnosis can prevent doctors from investigating physical causes. The case reinforces that when psychiatric symptoms don’t respond to standard treatment, or when objective physical signs emerge alongside psychiatric complaints, doctors must investigate organic (physical) causes.
This is a single case report, so we cannot generalize these findings to all patients with similar symptoms. The patient’s specific presentation, severity, and response to treatment may not be typical. We don’t know how common this type of misdiagnosis is, or whether other patients with B12 deficiency would recover as dramatically. Additionally, the case doesn’t provide information about what might have prevented the initial misdiagnosis—for example, whether a simple B12 blood test early on would have caught the problem. The case is most valuable as a warning sign for doctors to remain alert to the possibility of physical illness underlying psychiatric symptoms, rather than as proof of how often this occurs.
The Bottom Line
If you experience persistent fatigue, numbness, tingling, dizziness, and emotional distress that doesn’t improve with psychiatric treatment, ask your doctor to check your vitamin B12 level. This is a simple blood test that should be part of the initial workup for any new psychiatric symptoms. If you have both psychiatric symptoms and emerging physical signs (like weakness, loss of reflexes, or loss of sensation), insist on investigation for underlying medical causes. For healthcare providers: when patients present with psychiatric symptoms but show objective neurological signs or fail to respond to psychiatric treatment, investigate organic causes before assuming the condition is purely psychiatric. Early diagnosis and treatment of B12 deficiency is critical because nerve damage can become permanent if left untreated.
This case is relevant to anyone experiencing persistent psychiatric symptoms that don’t respond to treatment, especially if accompanied by physical symptoms like numbness, tingling, or weakness. It’s particularly important for people with risk factors for B12 deficiency, including those with pernicious anemia, digestive disorders, vegetarians and vegans, people taking certain medications (like metformin), and older adults. Healthcare providers should pay special attention to patients whose psychiatric symptoms don’t fit typical patterns or who fail to respond to standard psychiatric treatment. Family members of patients with unexplained psychiatric symptoms should encourage medical investigation beyond psychiatric evaluation.
In this case, the patient showed significant improvement within five months of starting B12 treatment. However, recovery timelines vary depending on how long the deficiency lasted and how much nerve damage occurred. Some nerve damage may be permanent if the deficiency goes untreated for too long. Early diagnosis and treatment offer the best chance for complete recovery. If you suspect B12 deficiency, seeking diagnosis and treatment promptly is critical—every month of delay increases the risk of permanent neurological damage.
Frequently Asked Questions
Can vitamin B12 deficiency cause depression and anxiety?
Yes, vitamin B12 deficiency can cause psychiatric symptoms including depression, anxiety, emotional distress, and cognitive problems. A 2026 case report documented a patient whose B12 deficiency presented as psychiatric illness for nine months before diagnosis. B12 is essential for nerve function and mood regulation, so deficiency affects both physical and mental health.
What are the warning signs that psychiatric symptoms might be caused by B12 deficiency?
Warning signs include psychiatric symptoms that don’t improve with standard treatment, combined with physical symptoms like tingling, numbness, weakness, balance problems, or absent reflexes. Fatigue, dizziness, and emotional distress lasting months warrant B12 testing. Early diagnosis prevents permanent nerve damage.
How long does it take to recover from vitamin B12 deficiency?
Recovery timelines vary based on deficiency duration and nerve damage severity. The documented case showed significant improvement within five months of treatment. However, nerve damage can become permanent if untreated for extended periods. Early diagnosis and treatment offer the best chance for complete recovery.
Who is at risk for vitamin B12 deficiency?
Risk groups include people with pernicious anemia, digestive disorders, vegetarians and vegans, those taking metformin or certain acid-reducing medications, and older adults. Anyone experiencing unexplained psychiatric or neurological symptoms should request B12 testing regardless of risk factors.
Should I ask my doctor to test my B12 level if I have depression?
Yes, especially if depression is new, severe, or doesn’t respond to standard psychiatric treatment. B12 testing is a simple blood test that should be part of initial psychiatric evaluation. Combined psychiatric and physical symptoms warrant investigation for medical causes like B12 deficiency.
Want to Apply This Research?
- Track three specific symptoms weekly: (1) energy level on a 1-10 scale, (2) presence of tingling or numbness in hands/feet (yes/no), and (3) mood on a 1-10 scale. If psychiatric treatment has been ongoing for more than 2-3 months without improvement, flag this pattern in the app to prompt a conversation with your doctor about investigating physical causes.
- If you’re being treated for psychiatric symptoms, use the app to document whether your symptoms are improving, staying the same, or worsening. Set a reminder to ask your doctor about B12 testing if you’ve been in treatment for 2-3 months without significant improvement. Keep a log of any new physical symptoms (numbness, weakness, balance problems) that emerge alongside psychiatric symptoms—this information is crucial for your doctor.
- Create a long-term symptom tracker that monitors both mental health (mood, anxiety, emotional distress) and physical symptoms (energy, numbness, coordination, balance). If you receive B12 treatment, track recovery progress across both categories. This dual-symptom approach helps identify whether improvement is occurring and whether the treatment is addressing the root cause rather than just masking symptoms.
This case report documents a single patient’s experience and should not be considered diagnostic guidance for your individual situation. Vitamin B12 deficiency can present with various symptoms, and not all psychiatric symptoms are caused by B12 deficiency. If you are experiencing psychiatric symptoms, depression, anxiety, or neurological symptoms like numbness or weakness, consult with a qualified healthcare provider for proper evaluation and testing. Do not discontinue psychiatric medications or treatment without medical guidance. This article is for educational purposes and does not replace professional medical advice, diagnosis, or treatment.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.