Esclerose Múltipla

A esclerose múltipla (EM) é uma doença do sistema nervoso central que frequentemente leva à invalidez. O sistema imunológico do corpo ataca e destrói por engano a bainha de mielina que protege e isola as fibras nervosas. A mielina aumenta a velocidade dos impulsos elétricos entre o cérebro e o resto do corpo e é essencial para que o sistema nervoso funcione normalmente. A perda de mielina faz com que estes sinais se tornem intermitentes ou interrompidos.

Os sintomas mais comuns associados à esclerose múltipla incluem fadiga, dificuldade em caminhar, espasmos musculares, dormência, fraqueza, problemas de visão, tontura, problemas de bexiga e intestinos, dores, depressão, alterações cognitivas e emocionais. Em casos raros podem ocorrer convulsões.

O tipo mais comum da doença é chamada de Esclerose Múltipla Recorrente-Remitente (EMRR), caracterizada por incidência diária ou semanal, podendo apresentar novos sintomas, seguida de períodos de remissão que podem durar meses ou anos. É comum que os pacientes diagnosticados com EMRR eventualmente apresentem uma transição para outro estágio chamado de Esclerose Múltipla Secundária Progressiva (EMSP), onde a doença progride, com ou sem reincidência. Outros tipos incluem a Primária Progressiva (EMPP), caracterizada por funções neurológicas que se agravam progressivamente com o passar do tempo e a EM Progressiva com Surtos (EMPS), que apresenta uma progressão contínua, mas com surtos eventuais.

A causa da esclerose múltipla continua desconhecida, mas sabe-se que a doença afeta principalmente as mulheres e indivíduos entre 15 e 60 anos de idade.

Não existe cura para a doença. O tratamento inclui administração de corticosteroides para reduzir a inflamação dos nervos e a plasmaférese (remoção de plasma, ou a retirada de sangue com separação dos glóbulos por centrifugação, substituindo-se o plasma por solução de Locke). Estas técnicas podem ajudar a controlar os sintomas e potencialmente limitar a progressão da doença.

Descobertas: efeito dos canabinoides na esclerose múltipla

Pesquisas têm sugerido que a canabis pode desacelerar o processo neurodegenerativo da esclerose múltipla. Alguns estudos têm demonstrado que os canabinoides estão envolvidos na regulação do sistema imunológico ao interagir com os receptores do sistema endocanabinoide. Os canabinoides já demonstraram que podem influenciar a reação inflamatória e auxiliar na neuroregeneração 7,13,22. Em um estudo com animais, os canabinoides demonstraram efeitos neuroprotetores, reduzindo os danos na mielina causados pela inflamação 23. Outro estudo descobriu que os canabinoides administrados em animais com um modelo de esclerose múltipla reduziu a impotência neurológica, melhorou a coordenação motora e limitou a progressão da doença 8.

A canabis pode ajudar os pacientes com esclerose múltipla a controlar os sintomas associados à doença. Ela demonstrou ainda ser eficaz na redução de dor, rigidez e espasmos musculares 11,30. Em outro estudo, pacientes com EM obtiveram melhorias significativas na espasticidade muscular e diminuição dos distúrbios do sono após quatro semanas em tratamento com canabis 19. Um estudo semelhante descobriu que os pacientes com a doença experimentaram melhorias no sono e na sensibilidade à dor após cinco semanas de tratamento com THC (tetrahidrocanabinol) e CBD (canabidiol) 24.

Há evidências que sugerem que a canabis pode piorar problemas cognitivos em pacientes com esclerose múltipla. Pacientes com a doença que eram usuários habituais de canabis (encontrada nas ruas) tiveram resultados significativamente inferiores em testes de função cognitiva 10,21.

Estudos recentes sobre os efeitos da canabis na esclerose múltipla

• Os canabinoides foram eficazes na redução da incapacidade neurológica e na progressão da doença em camundongos com uma forma animal de esclerose múltipla. Os canabinoides amenizam a progressão da doença em um modelo de esclerose múltipla em camundongos, agindo preferencialmente através dos efeitos anti-inflamatórios mediados pelo receptor CB1.
  (http://www.sciencedirect.com/science/article/pii/S0028390812000500)

• Quatro semanas de tratamento com canabis levaram a melhorias significativas nos espasmos de pacientes com EM. Um estudo randomizado duplo-cego-placebo-controlado, de grupos paralelos e design enriquecido de Nabiximols* (Sativex®), como terapia adicional em indivíduos com espasticidade refratária causada pela esclerose múltipla.(http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1468-1331.2010.03328.x/full)

• Cinco semanas de tratamento com canabis reduziu significativamente as dores e melhorou o sono de pacientes com esclerose múltipla. Estudo clínico controlado e randomizado com medicamento à base de canabis em dores centralizadas da EM.
  (http://www.neurology.org/content/65/6/812.long)

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