Impairment of the blood-brain barrier as an aetiological factor in paranoid psychosis.

Possible psychiatric implications of impairment of the blood-brain barrier were studied in 25 patients with paranoid psychosis. Determination of the ratio between the albumin concentrations in cerebrospinal fluid and serum showed increased, indicating impairment of the blood-brain barrier, in seven patients and normal values in 18. The two groups were compared for clinical, pharmacokinetic, neurophysiological and anamnestic variables. The highly significant finding that onset of psychosis had occurred, on average, 20 years earlier in the patients with impairment of the blood-brain barrier than in those without suggests that such impairment might influence the development of psychosis in predisposed individuals.