Emil Kraepelin was a pioneer of the diagnosis of mental disorders. Among the categories he identified were , which is similar to the current label of bipolar disorder, and , which is similar to the current label of schizophrenia.

manic-depressive psychosis; dementia praecox      

Explanation:    

Manic-depressive psychosis is also referred to as bipolar disorder and is defined as the process through which an individual experience alternating mood of either abnormal low i.e, depression or abnormal highs i.e, mania. In short, a person experiences the "swings" between the opposing poles or differences in moods. It is considered as a "depressive disease" and includes psychosis symptoms.

Dementia praecox is also referred to as precocious madness or premature dementia and is described as a psychiatric diagnosis that is considered as deteriorating & chronic psychotic disorder which is distinguished as "rapid cognitive integration" and starts at early adulthood or late teenagers.

i would say b. research typically uses a variety of sources

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