Russian to English Medical Medical (general) mental health

I'm translating a clinical trial investigating use of an antidepressant drug to treat depression in patients with schizophrenia. It's available at http://www.mediasphera.ru/uppic/Zhurnal nevrologii i psikhia...

My problem is, what's the difference between анксиозные проявления and тревога? I understand them both to mean 'anxiety'. However, the results show that patients experienced increased or reduced тревога during the trial attributed to the action of the drug studied, but the text also states that they were allowed to use an additional drug 'Для коррекции анксиозных проявлений или расстройств сна'.

It seems to me that the use of this additional drug would invalidate the results of the trial if анксиозные проявления and тревога are synonyms, as how could you tell which action is achieved by the drug studied and which by the additional drug?

And moreover, how should I translate анксиозные проявления and тревога? I'm thinking of 'anxiety' and 'alarm'.

Thank you in advance for any input.

Fiona