A large study of 4,444 consecutive patients in Taiwan found that those with low total cholesterol (<160 mg/dL) had higher scores of anxiety, phobia, psychoticism, and aggressive hostility.17 In the same study, women with low high-density lipoprotein cholesterol (<35 mg/dL) had significantly higher scores for depression, phobia, anxiety, interpersonal sensitivity, somatization, and aggressive hostility.17
Not surprisingly, low cholesterol has been proposed as a biomarker for mood dysregulation, depression, and suicidality,18 as well as a predictor of the depression severity and increased suicide risk.19 Clinical recovery in depression may be accompanied by a significant increase of total cholesterol20 but, interestingly, a decrease in cholesterol levels after treatment of mania. High cholesterol was reported to predict poorer response to selective serotonin reuptake inhibitors, and total cholesterol levels >200 mg/dL were associated with lack of response to fluoxetine and nortriptyline.2 Interestingly, clozapine, which elevates lipids, exerts a strong anti-suicide effect in schizophrenia and schizoaffective disorder, but that may not be the main reason for its efficacy in preventing suicide in patients with psychosis.
Cholesterol is an important lipid for brain function. At lower levels, it appears to be associated with depression, suicide, violence, anxiety, schizophrenia, and severe personality disorders (including antisocial personality disorder and borderline personality disorder). However, at high levels, it may improve cognition in schizophrenia and ameliorate the pace of AD and neurodegeneration. Psychiatrists should monitor patients for hypercholesterolemia and hypocholesterolemia, both of which are common among psychiatric patients. High levels may be genetic or the result of weight gain, hypercortisolemia, diabetes, or immune or inflammatory processes. Similarly, low levels may be genetic or secondary to statin therapy.
The bottom line: As psychiatric physicians, we should protect both the hearts and brains of our patients.