Based on Clara's history, behaviours and symptoms, determine and explain the most likely diagnosis with supporting evidence. In your opinion, what makes the differential diagnosis difficult or chalenging for her case? Support your answer with what you have learnt ni the course, empirical evidence and examples.

Clara, a 26-year-old woman, has been admitted to a psychiatric hospital due to her alarming behavioural changes over the past few months. Clara’s symptoms in the past few months have been concerning and progressively getting worse. She has become increasingly withdrawn, spending most of her time alone in her room, avoiding contact with her family. Her behaviour has become erratic, and her family has noticed her talking to herself and laughing at seemingly random moments. Clara has been hearing voices that she believes are from deceased relatives. She trusts these voices and believes that they are guiding her day-to-day actions and decisions. Her family has become increasingly worried about her mental health, and they have brought her to a psychiatric hospital for evaluation and treatment. Upon admission to the psychiatric hospital, Clara displays a marked disorganisation in her speech, and her responses to questions are difficult to decipher, with her thoughts frequently meandering off-topic. Her thought process lacks coherence, often jumping abruptly from one topic to another, which is consistent with the manifestation of thought disorders. Clara has delusions and has expressed to the hospital staff that she has been communicating with her deceased relatives. Moreover, Clara’s hygiene has significantly deteriorated, which is an atypical behavioural change for her. Her family reports that Clara had always been meticulous about her grooming routine, but her personal appearance has degraded noticeably in recent months. Upon physical assessment, the hospital staff notes her dishevelled appearance, unkempt and soiled clothing, and suboptimal general hygiene. Notably, Clara has no history of substance abuse, head injuries or seizures.