When beginning your research, ask yourself the following questions. How much detail do you need? Do you require the latest research findings on the condition, or are you looking for a more general overview?
The type of resource that you search will often depend on your answer to these questions. Consider the following timeline, with established facts, methods, and models on one end and the most recent research published on a topic on the other.
Different sources will appear on the timeline at different places. Let's first consider where academic resources lie.
Academic journal articles report the findings of a study. They are focused on one issue or problem within a broader topic and typically offer recent (recent at the time of publication) developments on the topic. On the other hand, encyclopedias and other reference works are more likely to give an overview of a topic that has been developed over time, reporting the facts, methods and models that have been established and often agreed upon by the research community (it's important to note, however, that the nature of scholarly inquiry means that there will be opposing theories that do not always agree). In covering so much material, encyclopedia articles do not cover the topic deeply (they exhibit breadth, not depth of coverage). Books straddle this void. They give more in-depth coverage of a topic than reference works. They cover a topic more broadly than a journal article. Sometimes, depending on the field, they will also include recent research developments.
Now, let's consider where common internet sources fall on the timeline.
Reports from news agencies typically highlight the finding of a recent study that has been deemed interesting by the press, often paraphrasing an academic journal article's results section. In contrast, websites of organizations that focus on the condition as well as prominent medical and governmental departments will contain a mix of information. You'll often be able to locate background information that has been written for a public audience as well as relevant findings from recent studies. That makes them a good place to look for information on your topic.