Pituitary Volume in First Episode Psychosis: A Structural MRI Study

Ameet R. Upadhyaya, Rhonda El-Sheikh, Matcheri S. Keshavan

Psychiatry & Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI

Background: Hypothalamic-pituitary-adrenal (HPA) axis dysfunction may play an etiological role in psychosis. Abnormal pituitary volume can be one indicator of HPA dysfunction. Since antipsychotic medication can affect pituitary size, antipsychotic-naïve patients are the ideal population to investigate pituitary volumes.
Methods: Pituitary volumes were measured in first episode psychotic patients (FE: n = 51) and controls (C: n=55). Measurements were conducted on 1.5 mm thick T1-weighted coronal images from a 1.5T GE scanner using BRAINS2 software by two trained raters.
Results: FE had smaller pituitary volumes than control subjects (mean volume ± s.d. = 0.58 ± 0.14 mm³ and 0.66 ± 0.17 mm³ respectively; ANCOVA, F = 6.3264, p = 0.014). When comparing all males (patients and controls) versus all females (patients and controls), there was increased pituitary volumes among females (F = 10.427, p = 0.002). However, this gender distinction disappeared when comparing male patients versus female patients (F = 3.317, p = 0.08).
Conclusions: Our study indicates that pituitary volume is reduced in patients with first episode psychosis. To our knowledge, this is the first study that reports reduced volumes in an antipsychotic naïve population. Repeated activation of the HPA axis leading to psychosis may result in elevated cortisol levels. These levels may have inhibitory effects on pituitary corticotrophs leading to a reduction in gland size. Similar pituitary volume reductions have been seen by us in bipolar patients and may cut across diagnostic boundaries. Previous studies showing larger volumes in these populations may have been confounded by treatment effects.