Do you think it is true that Judy Garland had undiagnosed bipolar disorder?

I have read a few books on the life of Judy Garland and there has been some speculation that she was an undiagnosed manic depressive.Her daughter Liza Minnelli thinks her mother had the condition as she said that a few years before her mother died she would have extreme mood swings.Periods where she would be in bed for days with severe depressions and periods where she would be awake for days with severe agitation and irritability, full blown rages, delusions, paranoia and hallucinations.Do you think this is true?Perhaps her heavy drug use exacerbated her illness.Thanks