Platelet MAO activity and family history of schizophrenia.

Platelet monoamine oxidase (MAO) activity was studied in 50 drug-free schizophrenics divided into groups according to whether they had at least two first-degree relatives with schizophrenia (n = 6), only one first-degree relative with schizophrenia (n = 8), or no family history of schizophrenia (n = 36). Similar determination was made in 56 age-matched normals. There were no differences in the platelet MAO activity between any of the groups of schizophrenics or the normals. The results are discussed in light of previous studies of platelet MAO activity in schizophrenics with and without a family history of schizophrenia.