In his review of psychiatric theories that tried to explain the manifestation of schizophrenia in the 20th century, Heinz criticized the use of Eurocentric developmental models.

Heinz shows that such theories are internally inconsistent, project an oversimplified model of brain development onto social interactions, and fail to recognize that allegedly "primitive" populations, at the beginning of the 20th century, were subjected to European imperialism and colonialism.

[10] Heinz emphasizes the impact of social and political ideas as well as racist prejudices on the historical development of research paradigms and theories regarding mental disorders.

[13][14] Transferring ideas on dopamine function from addiction research to schizophrenia, he suggested that in psychosis, chaotic or stress-associated phasic increases in striatal dopamine release attribute salience to otherwise irrelevant stimuli and thus contribute to delusional mood, a hypothesis later also supported by Shitij Kapur.

[13][15] Further empirical studies of Heinz and coworkers falsified simple top-down models of cerebral dysfunction in psychotic disorders; instead, his findings confirmed complex interactions between brain areas computing reward-related prediction errors, processing appetitive and threatening stimuli as well as contributing to fluid intelligence.

[17] He suggested that social isolation stress and discrimination are key factors interacting with basic cognitive functions as well as general mental health.

With respect to clinical practice, Heinz suggests that medically relevant symptoms of mental disorders such as a delirium or dementia are directly life-threatening, while key symptoms of psychosis and major affective disorders can impair the ability of an afflicted person to live with others, e.g. because own intentions and acts are attributed to outside forces such as "imperative acoustic hallucinations" or "inserted thoughts".