When did Britney Spears have a breakdown? What major event happened to Britney Spears the year after #1? What was the reason behind #2 happening to Britney Spears?
Bipolar disorder
In 2008 Britney Spears was detained in a psychiatric hospital for bipolar disorder. In 2007 Britney Spears shaved her head during a breakdown. 
mental disorder that causes periods of depression and abnormally elevated mood
Is Britney Spears' breakdown attributed to bipolar disorder?