Cognitive profile in dementia associated with vitamin B12 deficiency due to pernicious anaemia

Neuropsychiatric manifestations in vitamin B12 deficiency

Vitamin B12 deficiency can have distressing neuropsychiatric symptoms. It can have an etiological role in clinical presentations like depression, anxiety, psychosis, dementia, and delirium, requiring screening of at-risk populations. Few mechanisms that underlie the neuropsychiatric manifestations of B12 deficiency include alteration in one-carbon metabolism, genetic vulnerability, and alteration in folate metabolism. Maintaining a high serum B12 level in elderly can be protective against Alzheimer's disease (AD). In an established AD, its deficiency is associated with higher cognitive decline and risk for delirium. The other mental changes associated with B12 deficiency include apathy, agitation, impaired concentration, insomnia, persecutory delusions, auditory and visual hallucinations, and disorganized thought-process. Besides serum vitamin B12, plasma methylmalonic acid (MMA) and homocysteine helps in diagnosis. The chapter focuses on early recognition and effective treatment of these neuropsychiatric manifestations of vitamin B12 deficiency.

[Postoperative dementia: toxicity of nitrous oxide]

INTRODUCTION

Post-operative neuropsychiatric manifestations represent a frequent situation and may be due to several aetiologies. The responsibility of vitamin B12 deficiency must be evoked, especially in case of anaesthesia with a currently used substance: nitrous oxide.

CASE REPORT

A 65 year-old man with no medical history, presented problems walking and memory loss 16 days after surgery for femoral prosthesis. Neurological examination revealed paraplegia with syndrome of combined degeneration of the spinal cord. The exploration of cognitive functions showed disorientation in time with memory disorders and disturbance of executive functioning. There was no apraxia, aphasia or agnosia. There were neither psychotic symptoms nor mood changes. MMS was at 18/30. Red blood count revealed an anaemia with macrocytosis (MGV=120 3). Vitamin B12 rate was very low (less than 30 g/l). Folate blood level was normal. Brain MRI showed moderate cerebral atrophy. Other investigations led to the diagnosis of Biermer's disease (fundic atrophy at biopsy with presence in the serum of antibodies to intrinsic factor). The diagnosis of neurological attack related to a vitamin B12 deficiency secondary to Biermer's disease was established, but the appearance of disorders in the post-operative period suggested the existence of an added factor. The recovery of informations revealed that anaesthesia was maintained by nitrous oxide during two hours and the patient exhibited pre-operative anaemia with macrocytosis. The hypothesis of decompensation of latent vitamin B12 deficiency by nitrous oxide was evoked. Replacement therapy by vitamin B12 induced real improvement of the cognitive impairment. MMS increased to 25/30.

DISCUSSION

Cognitive impairment due to vitamin B12 deficiency is rarely dominated by isolated memory disorders. An authentic dementia is exceptional. Our patient had a dementia diagnosed on the basis of DSM IV criteria including memory disorders, disturbance of executive functioning and significant impairment in social and occupational functioning, associated with a combined degeneration of the spinal cord, common in vitamin B12 deficiency. Furthermore, he had an unknown Biermer's disease responsible for pre-operative deficiency which was clinically latent (there was only macrocytosis anaemia). The appearance of problems in the post-operative period was due to an acute decompensation of the latent deficiency induced undoubtedly by nitrous oxide used in anaesthesia. According to Christensen, nitrous oxide causes irreversible oxidation of vitamin B12 cobalt's atom responsible for its inactivation and the appearance of clinical manifestations. Evolution under vitamin B12 replacement therapy depends on the rapidity of its founding. In our case, it led to an improvement, notably in cognitive functions.

CONCLUSION

Through this observation, the authors underline the necessity to search for vitamin B12 deficiency in the case of cognitive features following general anaesthesia.

Vitamin B12 and folate depletion: clinical evidence in a neurological population

In cross-sectional studies, low levels of folate and vitamin B12 have been associated with poor cognition and dementia. Results are quite controversial and a debate continues in the literature. Still not completely understood are the differential roles of folate and vitamin B12 in memory acquisition and cognitive development. More intriguing and not fully understood is the rule that treating a vitamin B12-deficient patient with folate may exacerbate the neurological consequences of either deficiency. Starting from these quite confusing perspectives, the aim of this study was to define a possible role of vitamin B12 and folate in cognitive disruption. Data were collected among a cohort of people, admitted to the Neurology Clinic of the University of Trieste, in a period between November 1,2000, and November 1, 2002. We examine potential risk factors, concomitant drug-therapies, and cognitive global performance and correlate these parameters with folate and vitamin B 12 serum levels.We discuss the results with an overview of the literature.

[The role of nutritional factors on the structure and function of the brain: an update on dietary requirements]

The brain is an organ elaborated and functioning from substances present in the diet. Dietary regulation of blood glucose level (via ingestion of food with a low glycemic index ensuring a low insulin level) improves the quality and duration of intellectual performance, if only because at rest the adult brain consumes 50 p. 100 of dietary carbohydrates, 80 p. 100 of them for energy purposes. The nature of the amino acid composition of dietary proteins contributes to good cerebral function; tryptophan plays a special role. Many indispensable amino acids present in dietary proteins help to elaborate neurotransmitters and neuromodulators. Omega-3 fatty acids provided the first coherent experimental demonstration of the effect of dietary nutrients on the structure and function of the brain. First it was shown that the differentiation and functioning of cultured brain cells requires omega-3 fatty acids. It was then demonstrated that alpha-linolenic acid (ALA) deficiency alters the course of brain development, perturbs the composition and physicochemical properties of brain cell membranes, neurones, oligodendrocytes, and astrocytes (ALA). This leads to physicochemical modifications, induces biochemical and physiological perturbations, and results in neurosensory and behavioral upset. Consequently, the nature of polyunsaturated fatty acids (in particular omega-3) present in formula milks for infants (premature and term) conditions the visual and cerebral abilities, including intellectual abilities. Moreover, dietary omega-3 fatty acids are certainly involved in the prevention of some aspects of cardiovascular disease (including at the level of cerebral vascularization), and in some neuropsychiatric disorders, particularly depression, as well as in dementia, notably Alzheimer's disease. Their deficiency can prevent the satisfactory renewal of membranes and thus accelerate cerebral aging. Iron is necessary to ensure oxygenation, to produce energy in the cerebral parenchyma, and for the synthesis of neurotransmitters. The iodine provided by the thyroid hormone ensures the energy metabolism of the cerebral cells. The absence of iodine during pregnancy induces severe cerebral dysfunction, leading to cretinism. Manganese, copper, and zinc participate in enzymatic mechanisms that protect against free radicals, toxic derivatives of oxygen. The use of glucose by nervous tissue implies the presence of vitamin B1. Vitamin B9 preserves memory during aging, and with vitamin B12 delays the onset of signs of dementia, provided it is administered in a precise clinical window, at the onset of the first symptoms. Vitamins B6 and B12, among others, are directly involved in the synthesis of neurotransmitters. Nerve endings contain the highest concentrations of vitamin C in the human body. Among various vitamin E components, only alpha-tocopherol is involved in nervous membranes. The objective of this update is to give an overview of the effects of dietary nutrients on the structure and certain functions of the brain.

Visual failure caused by vitamin B12 deficiency optic neuropathy

Optic neuropathy is a rare but recognised complication of vitamin B12 deficiency, which may proceed to visual failure if not diagnosed early enough. Clues to the possible diagnosis include a history of, or risk factors for, pernicious anaemia, or previous resective gastrointestinal surgery.

In what extent anemia coexists with cognitive impairment in elderly: a cross-sectional study in Greece

BACKGROUND

A project aimed at studying the frequency of dementia and depression in the catchment area of the Health Centre of Chrissoupolis (HCCh), Northern Greece, was carried out. This paper reports the association between AD and anemia among the elderly participants in this Greek study.

METHODS

Eligible participants were people 65 years or over who were (a) living in the Elderly People's Home (all 48 subjects included); (b) visiting the Open Center for Elderly People during a 20 workday period (75 subjects) and (c) visiting the HCCh for routine medical care. The Mini Mental State Examination (MMSE) was used in assessing the cognitive capacity of the participants. Blood was drawn for serum hematocrit, vitamin B12 and folate determination.

RESULTS

The prevalence proportions of possible cognitive impairment among anemic and non-anemic males were 55.6% and 34.4%, respectively (X2 = 5.8, d.f. = 1, p = 0.016). The corresponding proportions in females were 47.5% and 40.1 % (X2 = 1.1, d.f. = 1, p = 0.305). Using logistic regression analysis, age-group (>or= 80 yrs), type of Institute, vitamin B12 and anemia had significant independent associations with possible cognitive impairment.

CONCLUSIONS

Anemia is a frequent finding in elderly and it may be a risk factor for dementia, but the extent of the associated deterioration of cognitive impairment or the relation with AD is not known. GPs should be aware of this coexistence and recommend for screening, assaying and treating elderly people.

Homocysteine, vascular dementia and Alzheimer's disease

There is some evidence from recent observational studies that hyperhomocysteinemia is a risk factor for cognitive dysfunction, including Alzheimer's disease and vascular dementia. There are only a few intervention studies, and the results are disappointing for such a frequent disease. Prospective double-blind and placebo-controlled intervention studies are not available. If homocysteine-lowering therapy will be in the running for the prevention and treatment of dementia, we must be able to diagnose the disease at a preclinical stage (i.e. 5 or 10 or 20 years before the disease becomes clinically overt for Alzheimer's disease). At the moment, there are insufficient data to support a vitamin B12, B6 or folate therapy in the prevention or treatment of patients with dementia.