It will be a research paper and you will need to use sources other than the book and NOT any .com websites. Research articles from scientific journals are preferred. Make sure its in APA format and cite throughout. Length should be about 3 pages in writing not including references, title or abstract (if you choose to include an abstract). The topic: pick any PD you are interested in and explore it in the paper. Focus on the development, population prevalence, treatment, co-morbidities (substance abuse, suicide etc) and any additional information you find that is interesting to you.