Diffusion tensor tractography and neuropsychological assessment in patients with vitamin B12 deficiency

The relationship between nutritional status and white matter integrity in older adults: A diffusion tensor imaging study

OBJECTIVES

The purpose of this study to determinate whether there is a relationship between the nutritional status and white matter integrity in older patients by using Diffusion Tensor Imaging (DTI).

METHODS

The patients were evaluated by Mini-Nutritional Assessment Scale. The patients are categorized in the groups of well-nourished, risk of malnutrition, or malnourished, depending on the overall score> 23.5, 17-23.5, or 17; respectively. All patients had brain MRI and DTI. The mean diffusivity (MD), fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD) values were calculated by ROI-based method in white matter tracts.

RESULTS

Total of the 224 patients; 86 patients had normal nutrition status (group 1), 107 patients were diagnosed with malnutrition risk (group 2) and 31 patients were diagnosed with malnutrition (group 3). Significantly decreased FA values of genu of corpus callosum, forceps minor and significantly increased MD values of middle cerebellar peduncle, and superior frontooccipital fasciculus were detected in group 2 in comparison to group 1 (p < 0.05). After adjusting for the folate and age, MD and RD values of cingulum remained significantly higher and the AD values of superior cerebellar peduncle remained significantly lower in group 3 (p < 0.05).

CONCLUSIONS

Malnutrition was associated with deteriorated DTI values, especially in cingulum and superior cerebellar peduncle. Assessing the nutritional status of older individuals is crucial to avoid its negative impact on brain.

ADVANCES IN KNOWLEDGE

Early diagnosis of malnutrition-related impaired WM integrity is important for prevention and intervention, and DTI is a useful non-invasive technique to be used for this purpose.

Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus

Background/Objectives: Vitamin B12 deficiency can cause variable symptoms, which may be irreversible if not diagnosed and treated in a timely manner. We aimed to develop a widely accepted expert consensus to guide the practice of diagnosing and treating B12 deficiency. Methods: We conducted a scoping review of the literature published in PubMed since January 2003. Data were used to design a two-round Delphi survey to study the level of consensus among 42 experts. Results: The panelists agreed on the need for educational and organizational changes in the current medical practices for diagnosing and treating B12 deficiency. Recognition of clinical symptoms should receive the highest priority in establishing the diagnosis. There is agreement that the serum B12 concentration is useful as a screening marker and methylmalonic acid or homocysteine can support the diagnosis. Patient lifestyle, disease history, and medications can provide clues to the cause of B12 deficiency. Regardless of the cause of the deficiency, initial treatment with parenteral B12 was regarded as the first choice for patients with acute and severe manifestations of B12 deficiency. The use of high-dose oral B12 at different frequencies may be considered for long-term treatment. Prophylactic B12 supplementation should be considered for specific high-risk groups. Conclusions: There is a consensus that clinical symptoms need to receive more attention in establishing the diagnosis of B12 deficiency. B12 laboratory markers can support the diagnosis. The severity of clinical symptoms, the causes of B12 deficiency, and the treatment goals govern decisions regarding the route and dose of B12 therapy.

Relation between Vitamin B12 Levels and Smell Affection in COVID-19 Patients

Introduction  Olfactory and gustative alterations are frequent in the initial stages of the COVID-19 infection. Vitamin B12 deficiency has been linked to olfactory dysfunction.

Objective  The present study aimed to assess the relationship between vitamin B12 levels and smell affection in COVID-19 patients.

Methods  The present study included 201 laboratory-confirmed COVID-19 patients. Smell affection was assessed using self-rated olfactory function. Serum vitamin B12 levels were assessed using commercial enzyme-linked immunosorbent assay (ELISA) kits.

Results  According to the smell function assessment, the patients were classified into three categories: normal osmesis ( n  = 77), hyposmia ( n  = 49), and anosmia ( n  = 75) ( Fig. 1 ). Four weeks later, 195 patients (97.0%) had their normal smell function restored. The remainder 6 patients included 4 anosmic and 2 hyposmic patients. Patients with hyposmia or anosmia had significantly lower vitamin B12 levels when compared with patients with normal osmesis (median [IQR]: 363.0 [198.0–539.0] versus 337.0 [175.0–467.0] and 491.0 [364.5–584.5] pg/ml, respectively, p  < 0.001).

Conclusion  Vitamin B12 appears to have some contribution to smell affection in patients with COVID-19 infection.

Brain Circuit Alterations and Cognitive Disability in Late-Onset Cobalamin D Disorder

Neuroimaging studies describing brain circuits' alterations in cobalamin (vitamin B12)-deficient patients are limited and have not been carried out in patients with inborn errors of cobalamin metabolism. The objective of this study was to assess brain functionality and brain circuit alterations in a patient with an ultra-rare inborn error of cobalamin metabolism, methylmalonic aciduria, and homocystinuria due to cobalamin D disease, as compared with his twin sister as a healthy control (HC). We acquired magnetic resonance imaging (including structural, functional, and diffusion images) to calculate brain circuit abnormalities and combined these results with the scores after a comprehensive neuropsychological evaluation. As compared with HC, the patient had severe patterns of damage, such as a 254% increment of ventricular volume, pronounced subcortical and cortical atrophies (mainly at striatum, cingulate cortex, and precuneus), and connectivity alterations at fronto-striato-thalamic circuit, cerebellum, and corpus callosum. In agreement with brain circuit alterations, cognitive deficits existed in attention, executive function, inhibitory control, and mental flexibility. This is the first study that provides the clinical, genetic, neuroanatomical, neuropsychological, and psychosocial characterization of a patient with the cobalamin D disorder, showing functional alterations in central nervous system motor tracts, thalamus, cerebellum, and basal ganglia, that, as far as we know, have not been reported yet in vitamin B12-related disorders.

Rationalization of Using the MR Diffusion Imaging in B12 Deficiency

Context:

The structural imaging of brain does not demonstrate any changes in the vast majority of patients with vitamin B12 deficiency, even in the advanced stages.

Aims:

We investigated the microstructural changes in the brain with diffusion imaging among patients with biochemical evidence of B12 deficiency.

Patients and Methods:

We retrospectively analyzed all diffusion-weighted MRI images between the periods 2014–2016 who had biochemical evidence of B12. The age-sex matched controls were chosen from the group with normal B12 levels. Patients with pathological findings in conventional MRI images were excluded from the study.

Results:

About 37 patients were recruited (22 women, 15 men; mean age, 34.1 ± 9.9 years; age range). They were about thirty-four age-and sex-matched controls (with normal B12 levels), which were also included in the study. The mean apparent diffusion coefficient (ADC) value of amygdala (773.8 ± 49.9 vs. 742.2 ± 24.2, P = 0.01), hypothalamus (721.3 ± 39.2 vs. 700.2 ± 38.2, P = 0.02), striate cortex (737.6 ± 77.6 vs. 704.3 ± 58.2, P = 0.04), suprafrontal gyrus (740.7 ± 46.9 vs. 711.6 ± 40.7, P = 0.007) and medulla oblongata-olivary nucleus (787.3 ± 56.4 vs. 759.7 ± 46.2, P = 0.02) were significantly higher in B12 deficiency group compared to controls, whereas ADC values were similar at hippocampus, thalamus, insula, corpus striatum, cingulate gyrus, occipital gyrus, dentate nucleus, cerebral pedicle, tegmentum, pons, and posterior medulla oblongata.

Conclusions:

Our study indicates that a significant increase in ADC values occurs in multiple brain regions in patients with vitamin B12.

Subcortical lesions due to cobalamin deficiency: an unusual MRI lesion pattern

We present a 44-year-old male patient with new onset of right focal epilepsy and bilateral hand hypesthesia. Cerebral MRI showed bilateral T2w/DWI hyperintense subcortical lesions in the cingulate gyrus, insula, and amygdala, whereas spinal MRI revealed a cervical posterior column lesion, corresponding to subacute combined degeneration. Laboratory workup revealed a cobalamin deficiency due to type A gastritis, and no evidence of antibodies associated with limbic encephalitis. After sufficient cobalamin substitution, the cerebral and spinal lesions gradually regressed. Our case represents a unique cerebral subcortical MRI lesion pattern in a patient with epilepsy and cobalamin deficiency. Thus, the latter represents an important differential diagnosis for autoimmune encephalitis.

Evaluation of diffusion tensor imaging changes and neurocognitive effects of asymptomatic vitamin B12 deficiency

Vitamin B12 plays an important role in the mechanisms which are responsible for myelinization in the central nervous system. It can particularly lead to hematological and neuropsychiatric symptoms when serum levels fall due to insufficient intake with diet or absorption problems. The purpose of this study was to show the cognitive effects in vitamin B12 deficiency cases that have not reached clinical symptom level using neuropsychological tests, and to show possible cerebral neuronal damage using diffusion tensor imaging (DTI) method. A total of 62 asymptomatic vitamin B12 deficiency patients and 40 healthy subjects were included in the study and both groups were subjected to Standardized Mini-Mental State Examination, Montreal Cognitive Assessment Test, Rey Auditory Verbal Learning Test, forward and backward digit span (WMS-R forward and backward), Visual Reproduction Subtest (WMS-III), Category Fluency Test, Trail Making (Trail A-B) (21) and Similarities (BENZ) tests. DTI examinations were performed on both groups. Patient group was determined to get lower scores in all neuropsychological tests compared to control group. In DTI examination, a significant decrease in FA values of bilateral hippocampus and a prominent increase in apparent diffusion coefficient (ADC) values were determined in the patient group compared to control group. In this study, it was determined that there was microstructural damage in the brain in the presence of vitamin B12 deficiency even in the asymptomatic period, and the patients revealed cognitive decline. In accordance with this result, early treatment of the easily diagnosed and treated vitamin B12 deficiency may prevent possible irreversible damage in the future.

Vitamin B12

The biosynthesis of B₁₂, involving up to 30 different enzyme-mediated steps, only occurs in bacteria. Thus, most eukaryotes require an external source of B₁₂, and yet the vitamin appears to have only two functions in eukaryotes: as a cofactor for the enzymes methionine synthase and methylmalonylCoA mutase. These two functions are crucial for normal health in humans, and in particular, the formation of methionine is essential for providing methyl groups for over 100 methylation processes. Interference with the methionine synthase reaction not only depletes the body of methyl groups but also leads to the accumulation of homocysteine, a risk factor for many diseases. The syndrome pernicious anemia, characterized by lack of intrinsic factor, leads to a severe, sometimes fatal form of B₁₂ deficiency. However, there is no sharp cutoff for B₁₂ deficiency; rather, there is a continuous inverse relationship between serum B₁₂ and a variety of undesirable outcomes, including neural tube defects, stroke, and dementia. The brain is particularly vulnerable; in children, inadequate B₁₂ stunts brain and intellectual development. Suboptimal B₁₂ status (serum B₁₂<300pmol/L) is very common, occurring in 30%-60% of the population, in particular in pregnant women and in less-developed countries. Thus, many tens of millions of people in the world may suffer harm from having a poor B₁₂ status. Public health steps are urgently needed to correct this inadequacy.

White matter integrity as a mediator in the relationship between dietary nutrients and cognition in the elderly

OBJECTIVE

We examined the association of nutrient intake with microstructural white matter integrity, and the role of white matter integrity in the association between nutrient consumption and cognition.

METHODS

This cross-sectional analysis included 239 elderly (age ≥ 65 years) participants of a multiethnic cohort. White matter integrity was measured with fractional anisotropy (FA) from diffusion tensor magnetic resonance imaging. Nutrient patterns were derived from principal component analysis based on energy-adjusted intake of 24 selected nutrients. Generalized linear models were used to assess the association between nutrient patterns and mean FA of 26 white matter tracts. Mediation analysis was used to determine whether FA mediates the nutrient-cognition relationship. All models were adjusted for age at time of scan, gender, ethnicity, education, caloric intake, and apolipoprotein genotype.

RESULTS

Among the identified 6 nutrient patterns, 1 (nutrient pattern 6, characterized by high intakes of Ω-3 and Ω-6 polyunsaturated fatty acids and vitamin E) was positively associated with FA. Those with the highest tertile of nutrient pattern 6 score had a mean of 0.01 (p = 0.01) higher FA value than those with the lowest tertile, similar to the effect of a 10-year decrease in age (b for age = -0.001, p = 0.01). FA mediated the relationship between nutrient pattern 6 and memory, language, visuospatial and speed/executive function, and mean cognitive scores.

INTERPRETATION

Our study suggests that older adults consuming more polyunsaturated fatty acids and vitamin E rich foods had better white matter integrity, and that maintaining white matter microstructural integrity might be a mechanism for the beneficial role of diet on cognition. Ann Neurol 2016;79:1014-1025.

Effect of vitamin B12 deficiency on olfactory function

BACKGROUND

Vitamin B12 plays a major role in the maintenance of central and peripheral nervous systems. Vitamin B12 deficiency may affect the spinal cord, brain, optic nerve, and peripheral nerve functions; however, the effect of vitamin B12 deficiency on olfactory function has not been studied, so our study aimed to investigate that.

METHODS

Thirty-nine patients with low vitamin B12 levels and 34 controls were included in the study. All participants had detailed otorhinolaryngological examinations and laboratory tests. The Sniffin' Stick test was used for analysis of olfactory function. The 2 groups were compared for smell test results. Correlations of smell test results with demographic and laboratory data were investigated in the vitamin B12-deficient group.

RESULTS

The threshold discrimination identification scores were (mean ± standard deviation) 28.04 ± 5.58 and 35.10 ± 2.84 in the vitamin B12-deficient and control groups, respectively (p < 0.001). In the vitamin B12-deficient group, hyposmia and anosmia were evident in 56.4% and 5.1% of the patients, respectively, but no subjects in the control group had olfactory dysfunction (p < 0.001). Correlation analysis showed that age and odor identification score showed a negative correlation (p < 0.001); however, there was a positive correlation between threshold, discrimination and identification (TDI) score and vitamin B12 levels.

CONCLUSION

In this study, we showed for the first time that olfactory dysfunction may be present in patients with vitamin B12 deficiency. Apart from a negative correlation of age with odor identification score, none of the other parameters studied showed correlations with olfactory dysfunction.

Vitamin B-12 concentration, memory performance, and hippocampal structure in patients with mild cognitive impairment

BACKGROUND

Low-normal concentrations of vitamin B-12 (VitB12) may be associated with worse cognition. However, previous evidence has been mixed, and the underlying mechanisms remain unclear.

OBJECTIVE

We determined whether serum VitB12 concentrations within the normal range were linked to memory functions and related neuronal structures in patients with mild cognitive impairment (MCI).

DESIGN

In a cross-sectional design, we assessed 100 amnestic MCI patients (52 women; age range: 50-80 y) with low- and high-normal VitB12 concentration (median split: 304 pmol/L) for memory functions with the use of the Auditory Verbal Learning Test. MRI was performed at 3 tesla (n= 86) for the estimation of the volume and microstructure of the hippocampus and its subfields as indicated by the mean diffusivity on diffusion-weighted images. With the use of a mediation analysis, we examined whether the relation between VitB12 and memory performance was partially explained by volume or microstructure.

RESULTS

MCI patients with low-normal VitB12 showed a significantly poorer learning ability (P= 0.014) and recognition performance (P= 0.008) than did patients with high-normal VitB12. Also, the microstructure integrity of the hippocampus was lower in patients with low-normal VitB12, mainly in the cornu ammonis 4 and dentate gyrus region (P= 0.029), which partially mediated the effect of VitB12 on memory performance (32-48%). Adjustments for age, sex, education, apolipoprotein E e4 status, and total homocysteine, folate, and creatinine did not attenuate the effects.

CONCLUSIONS

Low VitB12 concentrations within the normal range are associated with poorer memory performance, which is an effect that is partially mediated by the reduced microstructural integrity of the hippocampus. Future interventional trials are needed to assess whether supplementation of VitB12 may improve cognition in MCI patients even in the absence of clinically manifested VitB12 deficiency. This trial was registered at clinicaltrials.gov as NCT01219244.

Assessment of brain cognitive functions in patients with vitamin B12 deficiency using resting state functional MRI: A longitudinal study

INTRODUCTION

The resting state functional MRI (rsfMRI) approach is useful to explore the brain's functional organization in health and disease conditions. In this study, using rsfMRI the alteration in brain due to vitamin B12 deficiency and reversibility of these alterations following therapy was studied.

METHODS

Thirteen patients with clinical and biochemical evidence of vitamin B12 deficiency were recruited in this study. Fifteen age and sex matched healthy controls were also included. Patients and controls were clinically evaluated using neuropsychological test (NPT). The analysis was carried out using regional homogeneity (ReHo) and low frequency oscillations (LFO) of BOLD signals in resting state. Six patients were also evaluated with rsfMRI and NPT after 6 weeks replacement therapy.

RESULTS

ReHo values in patients with vitamin B12 deficiency were significantly lower than controls in the entire cerebrum and the brain networks associated with cognition control, i.e., default mode, cingulo-opercular and fronto-parietal network. There was no significant difference using LFO and it did not show significant correlations with NPT scores. ReHo showed significant correlation with NPT scores. All the 6 patients showed increase in ReHo after replacement therapy.

CONCLUSION

We conclude that brain networks associated with cognition control are altered in patients with vitamin B12 deficiency, which partially recover following six weeks of replacement therapy. This is the first study to evaluate the rsfMRI in the light of clinical neuropsychological evaluation in patients. rsfMRI may be used as functional biomarker to assess therapeutic response in vitamin B12 deficiency patients.

Assessment of functional and structural damage in brain parenchyma in patients with vitamin B12 deficiency: A longitudinal perfusion and diffusion tensor imaging study

INTRODUCTION

Vitamin B12 deficiency may cause neural tissue damage. Even in advanced stages, conventional imaging of brain usually appears normal in vitamin B12 deficient patients. The aim of this study was to assess the structural and functional changes in brain of patients with vitamin B12 deficiency before and after six weeks of vitamin B12 supplementation using diffusion tensor imaging and pseudo-continuous arterial spin labelling (PCASL).

METHODS

MR imaging including DTI and PCASL and neuropsychological tests (NPT) were performed in 16 patients with vitamin B12 deficiency and 16 controls before and after 6weeks of therapy. Cerebral blood flow (CBF) derived from PCASL and DTI indices was calculated in brain of patients with vitamin B12 deficiency and controls.

RESULTS

Patient with vitamin B12 deficiency showed altered neuropsychological scores and altered CBF as well as fractional anisotropy (FA) values in various brain regions as compared with controls. Both CBF values and neuropsychological scores showed complete reversibility at 6weeks post therapy. Though FA values showed significant recovery, it failed to show complete recovery.

CONCLUSION

Our results suggest that micro-structural recovery lags behind functional recovery in patients with vitamin B12 deficiency following therapy and CBF change may be used as an early predictor of complete recovery in patients with B12 deficiency.