Anna O. was the pseudonym of a patient of Josef Breuer, who published her case study in his book Studies on Hysteria, written in collaboration with Sigmund Freud. Her real name was Bertha Pappenheim (1859–1936), an Austrian-Jewish feminist and the founder of the Jüdischer Frauenbund (League of Jewish Women).
Anna O. was treated by Breuer for severe cough, paralysis of the extremities on the right side of her body, and disturbances of vision, hearing, and speech, as well as hallucination and loss of consciousness. She was diagnosed with hysteria. Freud implies that her illness was a result of the resentment felt over her father's real and physical illness that later led to his death.
Her treatment is regarded as marking the beginning of psychoanalysis. Breuer observed that whilst she experienced 'absences' (a change of personality accompanied by confusion), she would mutter words or phrases to herself. In inducing her to a state of hypnosis, Breuer found that these words were "profoundly melancholy fantasies...sometimes characterized by poetic beauty". Free association came into being after Anna/Bertha decided (with Breuer's input) to end her hypnosis sessions and merely talk to Breuer, saying anything that came into her mind. She called this method of communication "chimney sweeping", and this served as the beginning of free association.
Historical records since showed that when Breuer stopped treating Anna O. she was not becoming better but progressively worse. She was ultimately institutionalized: "Breuer told Freud that she was deranged; he hoped she would die to end her suffering".
She later recovered over time and led a productive life. The West German government issued a postage stamp in honour of her contributions to the field of social work.
According to one perspective, "examination of the neurological details suggests that Anna suffered from complex partial seizures exacerbated by drug dependence." In this view, her illness was not, as Freud suggested, psychological, but neurological. Professor of psychology Hans Eysenck and medical historian Elizabeth M. Thornton argued that it was caused by tuberculous meningitis. While some believe that Freud misdiagnosed her, and she in fact suffered from temporal lobe epilepsy, and many of her symptoms, including imagined smells, are common symptoms of types of epilepsy, others meticulously refute these claims.