Mental healthcare domain highlights the significance of trustworthiness between patient and psychiatrist for treatment process. In this paper, the issue of assessing psychiatrist trustworthiness from patient perspective, within a Ubiquitous Healthcare (UH) environment, is addressed. To meet that challenge, a Trust Assessment mechanism mimicking human cognitive judgment, is proposed. The exploitation of innovative fuzzy-probabilistic transformation model, denoted as cloud, for mechanism deployment enables fuzziness as well as adhered randomness of cognitive perception and assessment to be captured. A set of simulations within MATLAB software environment verify the introduced mechanism efficiency.