心跳加速、神经性发抖、精神亢奋甚至还有一点糊涂——如果你出现上述“症状”，那你一定是陷入热恋之中了。但意大利科学家现在要告诉你，这种美妙的感觉不会超过1年，也就是说你的热恋最多只能持续1年的时间。

　　据路透社11月30日报道，意大利帕维亚大学的研究人员表示，让刚坠入爱河的情侣疯狂相恋的是人体血液内的那些“爱情分子”——神经生长因子。

　　研究人员对58名正在热恋中的人们进行实验后发现，他们血液中的神经生长因子数量远远多于那些单身汉或是已建立起长期恋爱关系的人。但仅1年之后，那些当初热恋者体内的“爱情分子”的数量就下降到了普通人的水平。

　　他们同时指出，究竟怎样的恋爱方式可以让人体血液里的神经生长因子含量最高目前还不得而知。但是这种“爱情分子”确实在开始一段关系的人们的“交际化学”中起着重要作用。研究人员将此结果发表在了意大利最新一期的《神经心理内分泌学》杂志上。

　　Your heartbeat accelerates, you have butterflies in the stomach, you feel euphoric and a bit silly. It's all part of falling passionately in love -- and scientists now tell us the feeling won't last more than a year.

　　The powerful emotions that bowl over new lovers are triggered by a molecule known as nerve growth factor (NGF), according to Pavia University researchers.

　　The Italian scientists found far higher levels of NGF in the blood of 58 people who had recently fallen madly in love than in that of a group of singles and people in long-term relationships.

　　But after a year with the same lover, the quantity of the 'love molecule' in their blood had fallen to the same level as that of the other groups.

　　The Italian researchers, publishing their study in the journal Psychoneuroendocrinology, said it was not clear how falling in love triggers higher levels of NGF, but the molecule clearly has an important role in the "social chemistry" between people at the start of a relationship.