Made available in DSpace on 2014-12-17T14:13:32Z (GMT). No. of bitstreams: 1 MarcioLTA_Tese.pdf: 1453040 bytes, checksum: 7c0ed7c44a56eb54d2170012eedbfa04 (MD5) Previous issue date: 2009-11-27 / The imprecision of the frontier that separates those cognitive deficits inherent to the human physiological aging process from those which represent the early signs of nervous system degenerative pathologies ,very prevalent among the elderly, has brought attention to the need of studies aiming to establish clinical and/or laboratorial criteria to allow this differentiation. Elderly people living in poor and developing countries are frequently exposed to precarious socioeconomic conditions which facilitate the development of an array of pathologies which have metabolic and nutritional dysfunctions as the established or proposed etiological agents. The levels of certain micronutrients, such as the vitamins B12 and B9 (folic acid), and of some intermediary metabolites, such as homocysteine are being thought of as etiological factors and/or as biological markers of a group of alterations which affect the normal functioning of the nervous system with important reflexes upon cognitive performance. This study aims to investigate the influence of homocysteine, B12 vitamin and folic acid levels on the cognitive performance of the low income elderly population. This transversal study took place in Natal, Rio Grande do Norte State, Brazil, and involved 205 dwelling elderly people, users of the Programa de Sa?de da Fam?lia, a public healthcare program, maintained by the city s health authorities. A multidimensional questionnaire was used to assess the socio-demographic aspects and the overall health and nutrition conditions. The cognitive performance was measured by the use of the Portuguese version of the Mini Mental State Exam (MMSE). The serum levels of homocysteine, B12 vitamin and folic acid were determined by chemiluminescence. The association between the socio-demographic and serum levels of Hcy, B12 vitamin and folic acid was determined by multiple linear regression. Serum levels higher than 13.5 &#956;mol/l, indicative of hyperhomocysteinemia (HHcy), were found on 25.4% of the sample, being more prevalent in men (p<0.05). Deficitary levels of folic acid (<5ng/mol) and of B12 vitamin (<193 pg/ml) were found on 3.9% and 10.2% of the sample respectively. A negative correlation was found between cognitive performance with both age and HHcy and a positive correlation was found between cognitive performance and schooling. The isolated HHcy R2 values were an explanation to only 4% of the variance of the MMSE scores. However, when associated with schooling and age, this model explains about 25% of this association / A imprecis?o da fronteira que separa os d?ficits pr?prios do processo de envelhecimento fisiol?gico humano daqueles que representam os sinais precoces das patologias degenerativas de grande preval?ncia entre idosos, tem chamado a aten??o para a necessidade da produ??o de estudos voltados para o estabelecimento crit?rios cl?nicos e/ou laboratoriais que permitam essa diferencia??o. Idosos de popula??es de pa?ses pobres e/ou em desenvolvimento s?o freq?entemente expostos a condi??es socioecon?micas prec?rias prop?cias ao desenvolvimento de um conjunto de patologias, disfun??es metab?licas e nutricionais. Os n?veis de determinados micronutrientes e de alguns metab?litos intermedi?rios v?m sendo vistos como fatores etiol?gicos e como marcadores biol?gicos de um conjunto de altera??es que afetam a fun??o normal do sistema nervoso com reflexos importantes sobre o desempenho cognitivo. N?veis elevados de homociste?na (Hcy) e d?ficits nutricionais e /ou metab?licos da vitamina B12 e B9 (?cido f?lico) t?m sido apontados como preditores e/ou como fatores etiol?gicos de altera??es cognitivas. O objetivo desse estudo foi avaliar a influ?ncia dos n?veis de homociste?na, Vitamina B12 e ?cido f?lico no desempenho cognitivo de idosos de baixa renda. Este estudo transversal desenvolvido em Natal, Rio Grande do Norte, Brasil, incluiu 205 idosos n?o institucionalizados atendidos pelo Programa de Sa?de da Fam?lia da Secretaria Municipal de Sa?de do munic?pio. Um question?rio multidimensional foi utilizado para avaliar os aspectos sociodemogr?ficos e as condi??es gerais de sa?de e nutri??o. O desempenho cognitivo foi aferido utilizando-se a vers?o em portugu?s do Mini-Exame do Estado Mental (MEEM). Os n?veis s?ricos de homociste?na, Vitamina B12 e ?cido f?lico foram determinados por quimioluminesc?ncia. A associa??o entre as vari?veis sociodemogr?ficas e os n?veis s?ricos de Hcy Vitamina B12 e ?cido f?lico foi determinada atrav?s de regress?o linear m?ltipla. Valores s?ricos acima de 13,5 &#956;mol/l indicativos de hiperhomocisteinemia (HHcy) foram encontrados em 25,4% da amostra sendo mais prevalente em homens (p<0,05). N?veis deficit?rios de ?cido f?lico (<5ng/ml) e de Vitamina B12 (<193 pg/ml) foram encontrados em 3,9% e 10,2% dos indiv?duos respectivamente. O desempenho cognitivo mostrou uma correla??o negativa com a idade e a HHcy e positiva com a escolaridade. Os valores R2 da HHcy isolada explicaram apenas 4% da vari?ncia da pontua??o do MEEM. Contudo, quando associada escolaridade e idade, este modelo explica aproximadamente 25% desta associa??o.