Positron Emission Tomography Reveals Elevated D ₂ Dopamine Receptors in Drug-Naive Schizophrenics

TLDR

Postmortem studies have found increased D2 dopamine receptors in the basal ganglia of schizophrenia patients, though this may reflect drug‑induced adaptation rather than an intrinsic abnormality. The study used PET to quantify D2 receptor density in the caudate nucleus of healthy volunteers and both drug‑naïve and drug‑treated schizophrenia patients. Both drug‑naïve and drug‑treated schizophrenia patients exhibited higher caudate D2 receptor densities than healthy controls, indicating that schizophrenia itself is linked to increased D2 receptor density.

Abstract

In postmortem studies of patients with schizophrenia, D2 dopamine receptors in the basal ganglia have been observed to be more numerous than in patients with no history of neurological or psychiatric disease. Because most patients with schizophrenia are treated with neuroleptic drugs that block D2 dopamine receptors in the caudate nucleus, it has been suggested that this increase in the number of receptors is a result of adaptation to these drugs rather than a biochemical abnormality intrinsic to schizophrenia. With positron emission tomography (PET), the D2 dopamine receptor density in the caudate nucleus of living human beings was measured in normal volunteers and in two groups of patients with schizophrenia--one group that had never been treated with neuroleptics and another group that had been treated with these drugs. D2 dopamine receptor densities in the caudate nucleus were higher in both groups of patients than in the normal volunteers. Thus, schizophrenia itself is associated with an increase in brain D2 dopamine receptor density.