Membrane abnormalities in the psychoses and affective disorders.

Area of Science:

• Neuroscience
• Biochemistry
• Psychiatry

Background:

• Altered erythrocyte membrane composition has been observed in psychiatric disorders.
• Phosphatidylcholine (PC) is a key component of cell membranes, and its levels may vary in patients with psychotic or manic conditions.
• Lithium transport across red blood cell membranes is a potential biomarker for treatment response in certain psychiatric conditions.

Purpose of the Study:

• To investigate the relationship between erythrocyte membrane phospholipid composition, specifically phosphatidylcholine (PC), and lithium transport in patients with psychotic and/or manic disorders.
• To explore how variations in PC levels might influence sodium-lithium counterflow activity and passive lithium leak.

Main Methods:

• Erythrocyte ghost phospholipid data were collected from 67 patients diagnosed with psychotic and/or manic disorders and compared to 35 age- and sex-matched controls.
• Patients meeting DSM-III criteria for schizophreniform disorder or schizophrenia (without mania) were analyzed for membrane phosphatidylcholine (PC) levels.
• Lithium transport across red blood cell membranes was measured in 53 patients, and correlated with PC distribution quartiles.

Main Results:

• A significant decrease in membrane phosphatidylcholine (PC) was observed in patients with schizophreniform disorder or schizophrenia (but not mania) compared to controls.
• Patients in the upper quartile of PC distribution exhibited a significant 47% decrease in the 24-hour in vitro lithium ratio compared to those in the lower PC quartile.
• This reduction in lithium ratio was attributed to increased Na-Li+ counterflow activity, not altered passive lithium leak, in the higher PC group.

Conclusions:

• Erythrocyte membrane phosphatidylcholine (PC) levels are altered in patients with schizophrenia.
• Reduced PC levels are associated with altered lithium transport, specifically increased Na-Li+ counterflow activity.
• These findings suggest a link between erythrocyte membrane composition and lithium transport mechanisms relevant to the action of lithium in psychiatric treatment.