Brain atrophy or dystrophy in schizophrenia: when did it happen?

Delayed onset of prepulse inhibition deficits following kainic acid treatment on postnatal day 7 in rats

Abnormal activity in corticolimbic circuits during development may be a predisposing factor for schizophrenia. Permanent or temporary lesions of limbic structures such as the ventral hippocampus and basolateral amygdala in rats on postnatal day (PND) 7 result in functional changes similar to some behavioural and cognitive signs of schizophrenia. The present experiments tested whether transient increases in the neural activity of corticolimbic circuits on PND 7 would result in similar behavioural changes. Long-Evans rats were treated with either kainic acid (KA, 1.5 mg/kg, i.p.) or saline on PND 7 and tested for prepulse inhibition (PPI) of the acoustic startle response and spontaneous locomotor activity both in a novel environment and following amphetamine treatment before puberty (PND 35) and in early adulthood (PND 56). In subgroups of animals PPI was also measured following apomorphine administration (0.2 mg/kg) and spatial learning and memory were tested in the water maze. Rats treated with KA were indistinguishable from saline-treated animals on PND 35. However, on PND 56, KA-treated animals showed a subtle consistent decrease in PPI relative to control animals, but did not show increased sensitivity to the disruptive effects of a low dose of apomorphine on PPI. Locomotor responses to novelty or amphetamine were not reliably altered in the KA-treated animals. KA- and saline-treated animals performed similarly in the water maze. These results support the hypothesis that neural hyperactivity on PND 7 in rats causes behavioural changes in early adulthood that resemble some symptoms of schizophrenia. These pharmacological data suggest that the changes are not mediated by postsynaptic alterations in mesolimbic dopamine transmission.

Head size and schizophrenia

There is a small but intriguing body of literature which suggests that head size may be reduced in patients with schizophrenia. This literature sits alongside more substantial and compelling evidence that there is a reduction in cerebral volume in schizophrenia. As an extension of earlier work, measures of extracranial head size derived from standard anthropometric approaches were assessed in 44 patients and 46 control subjects. Head size was found to be normal in schizophrenia. The relationship of brain size to head size is elaborated.

If patients with schizophrenia have small brains, why don't they have small heads?

Although patients with schizophrenia have reduced brain size, there is no conclusive evidence that they have reduced head size. This begs the question: 'What is the precise relationship between head size and brain size?' We used a unique osteological collection to explore the relationship between external head measures and cranial capacity. The external measures accounted for, at most, 60% of the variance in cranial capacity - a value low enough to question the oft-assumed tight relationship between head measures and brain size. Obviously, various tissues and spaces [skull, sinus, muscle (frontalis, temporalis and occipitalis), subcutaneous fat and epidermal layers] contribute to head size without contributing to brain volume. The contribution of these other tissues and spaces tends to decrease the signal and increase the noise in the estimation of brain volume. Thus, it is understandable that patients with schizophrenia can have reduced cranial capacity and not reduced head size.

Left cerebral hemiatrophy and schizophrenia-like psychosis in an adolescent

A previous report of cerebral hemiatrophy and schizophrenia added to the list of neurodevelopmental abnormalities associated with schizophrenia. In a new case, the birth history indicated perinatal hemorrhage and prematurity (30-31 weeks of gestation). CT and MR imaging showed reduction in left hemisphere size with ventricular enlargement and mild skull thickening. Loss of periventricular white matter was detected. Changes in skull thickness, size of air cells and volume of the cranial vault may be measurable correlates of putative developmental abnormalities in schizophrenia.