Candidate neuroanatomic substrates of psychosis in old-aged depression.

1. The authors investigated the candidate neuroanatomic substrates underlying delusional thought disorder in old-aged depressed patients by using magnetic resonance imaging (MRI), and examined the relationship between volumes for individual brain structures and clinical correlates of particular relevance to depression: executive cognitive impairment and global severity of depression. 2. MR morphometry was performed on nineteen deluded depressed patients and 26 non-deluded depressed patients, all older than 55 years of age. Subjects were administered a neuropsychological test battery and measures of depression. 3. The absolute volume of prefrontal cortex (PFC) was smaller in the deluded depressed group than in non-deluded depressed group (131.79 +/- 37.26 ml vs. 152.65 +/- 26.13 ml, p = 0.03); a difference that was statistically significant even after adjusting for the effect of whole brain volume (p = 0.01). No group differences were observed in the volumes of the basal ganglia, the temporal lobes, the superior temporal gyri, the amygdala-hippocampal complex, the lateral ventricles, or whole brain. The relative volume of PFC correlated inversely and significantly with the index of Wisconsin Card Sorting Test (WCST) performance (r = -0.76, p < 0.01) in depressed patients. 4. PFC may be one of the candidate neuroanatomic substrates underlying delusional thought disorder in old-aged depression.