这种翻译,翻译错了会很可笑,会严重偏离其真实意思.意思大概如下,我不保证其准确性,仅供参考
大多数的治疗手段、治疗过程,可能占95%左右吧,仅仅是起到慰藉作用、心理作用（缓解作用,比如止疼作用,意思是治标不治本,甚至仅仅是心理作用）.针对一些疾病的治疗,不管是否真的管用,只要病人认为有效那就有效,这就是心理作用.
but the vast majority,some 95%,offers nothing more than the comfort effect
这是主句,这无需多讲,主要是-后面的内容
the strange and inadequately explained tendency of certain medical conditions
这句指明上句的comfort effect指的是the strange and inadequately explained tendency,奇怪并且为充分解释的tendency
to respond to anything the patient thinks is directed at treating them,
接上句的tendency,一般tendency后面用to,respond to a treatment 指medical condition某疾病对treatment某疗法的预后,的反应,的疗效
anything,任何治疗方法,只要是病人认定某种治疗方法的确是针对他们的状况所采用的
even when the treatment in question could not possibly have a direct effect on the disease.
甚至、即使这种疗法、这些治疗压根就没怎么真正起效.