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To the Editor: Vitamin B12 deficiency, although known to be associated with neuropsychiatric manifestations of varying nature, is an underdiagnosed entity. We present a case of Vitamin B12 deficiency manifesting as clozapine-resistant symptoms in a patient with schizophrenia, in the absence of any clinical signs of vitamin B12 deficiency. The patient showed significant clinical improvement with parenteral vitamin B12 supplementation. This case highlights the need for vitamin B12-level assessment in such cases, as it could play a significant role in determining the outcome of the psychiatric disorder.

Vitamin B12 deficiency, an often under-diagnosed condition, is associated with various neuropsychiatric manifestations. Psychiatric manifestations can be associated with vitamin B12 deficiency. These include depression, irritability, dementia, delirium, and hallucinations.1

There have been reports of B12 deficiency presenting as psychosis2,3 or as catatonia.4,5 The onset of the psychotic symptoms can occur after,2 in the presence of3,6 or in the absence5 of any overt clinical examination findings indicative of vitamin B12 deficiency.

We present a patient with signs of clozapine-resistant schizophrenia in whom there were no overt clinical signs or symptoms of vitamin B12 deficiency but who had low serum B12 levels. This patient improved significantly with parenteral vitamin B12 supplementation.

Case Report

“Ms. V,” a 27-year-old single woman, with a vegetarian diet, presented with more than 10 years of illness characterized by irritability and assaultive behavior, auditory hallucinations, delusions of reference, persecution, and misinterpretation, with significant acting-out behavior. She was diagnosed with paranoid schizophrenia as per ICD-10 criteria. She was treated with risperidone up to 8 mg, lithium 600 mg, and 13 sessions of electroconvulsive therapy. She did not improve significantly, and a decision to start her on clozapine was made. Investigations, including a complete hemogram, peripheral smear, fasting blood sugar, lipid profile, renal function test, liver function test, serum electrolytes, thyroid function test, electrocardiogram, and electroencephalogram, did not reveal any abnormality. She was started on clozapine, which was gradually increased up to 225 mg. She had side effects like hypersalivation, constipation, tremors, tachycardia; hence, clozapine was decreased to 200 mg. She had two episodes of generalized tonic–clonic seizures. Clozapine was subsequently decreased to 175 mg, and valproate up to a dose of 1,000 mg was initiated. She was maintaining well for 5 months, after which she had a relapse due to drug default. Subsequently, she was restarted on clozapine, which was increased up to 200 mg, along with valproate 1,000 mg and eight sessions of electroconvulsive therapy. She showed significant improvement and hence was discharged. She was maintaining well for 9 months.

However, she had a relapse of psychotic symptoms again while on regular medication. The Scale for the Assessment of Positive Symptoms (SAPS)7 rating at the time of admission was 33. Physical examination revealed pallor. Blood investigation results were as follows: hemoglobin: 9.7 (normal: 13–17) g/dl, MCV: 108.3 (normal: 80–101 fl), PCV: 31 (normal: 40–50 L/L), MCH: 33.7 (normal: 27–32 pg), MCHC: 31.2 (normal: 315–345 g/L. Serum vitamin B12 value at that time was 236 (normal: 174–878 pg/ml). Peripheral smear revealed a macrocytic normochromic picture with mild anisocytosis and hypersegmented neutrophils. The patient had no dermatological, neurological, or other physical findings suggestive of vitamin B12 deficiency, no coexisting medical history, and was not on any other medication. It was decided to administer her intramuscular vitamin B12 in view of the low serum value. She was given cyanocobalamin 1,000 μg/day daily for 1 month. She was maintained on an unchanged dose of clozapine 200 mg and valproate 750 mg. Within 1 to 2 days of vitamin administration, the patient was seen to have significant change in her ward behavior in the form of reduction of anger, fearfulness, and suspiciousness. Over the next week, she showed significant improvement in psychiatric symptoms, with prominent reduction of the delusions of persecution, reference, and auditory hallucinations. By the end of 1 month of daily parenteral supplements, the SAPS score came down to 10. She continues to be on the same medication combination and daily oral vitamin B12 preparation while also receiving monthly parenteral vitamin supplementation. She continues to be asymptomatic for more than 8 months since then, with a current SAPS score of 2. There is a significant improvement in her socio-occupational functioning, and she has gained complete insight into her illness, with regular medication adherence. Her current serum B12 level is 1,192 pg/ml, and MCV is 94.3 fl.

Discussion

This patient had a normal smear picture during the early part of her illness; hence this is unlikely to be organic psychosis caused by vitamin B12 deficiency. However, during the course of her illness, probably due to inadequate nutrition, she developed vitamin B12 deficiency. This is likely to have been a factor in her being a nonresponder to various antipsychotics, including clozapine, especially after an initial period of response to clozapine.

Vitamin B12 plays a very vital role in the central nervous system. It is vital for homocysteine methylation to methionine, which is necessary for the synthesis of s-adenosyl methionine, which is essential for neurotransmitter metabolism. Any abnormality in the methylation process has been hypothesized to be a possible biochemical basis for neuropsychiatric manifestations of vitamin B12 deficiency. The levels of an excitatory neurotoxin called methytetrahydrofolate are markedly elevated in vitamin B12 deficiency and may be responsible for neuronal destruction.8

The patient described in this report had a relapse of psychotic symptoms while on regular medication with clozapine and improved with parenteral B12 supplementation while other medications were unchanged. Psychiatric manifestations in the absence5 of any overt clinical examination findings indicative of vitamin B12 deficiency (including neurological symptoms) are worth noting. Psychiatric manifestations can occur before the levels of vitamin B12 are below 175 pg/L, and it has been proposed that the threshold needs to be increased to 550 pg/L.9

This case clearly highlights the role of vitamin B12 in treatment of schizophrenia nonresponsive to antipsychotics including clozapine and ECT. Earlier surveys have shown that a large number of psychiatric patients have low serum B12 levels, ranging from 6% to 15%.10 This case highlights the need for vitamin B12 measurement in the initial part of the disease process itself to assess whether it is a causative factor or whether the deficiency contributes to a poorer outcome. Co-existing B12 deficiency in a patient with psychosis maybe more frequent than B12 deficiency causing organic psychosis, but early initiation of parenteral B12 supplementation may be beneficial in both situations.

Dept. of Psychiatry, National Institute of Mental Health And Neurosciences (NIMHANS), Bangalore, India
Correspondence: Dr. Dhanya Raveendranathan, Dept. of Psychiatry, National Institute of Mental Health And Neurosciences, Bangalore, India; e-mail:
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