Ultrasound shows brain differences in depressed patients

Patients with major depressive disorder can show actual physical changes to the brain structure on sonographic evaluation, according to German researchers. One study found that depressed patients with a history of responding to serotonin reuptake inhibitors also had a high incidence of reduced echogenicity of the brain stem raphe. Another found that many patients diagnosed with depression also showed increased echogenicity in a specific area of the midbrain common in patients with Parkinson's disease.

Dr. Uwe Walter and colleagues in the departments of neurology and psychiatry and psychotherapy at the University of Rostock performed both studies. The first was published in the May 15 issue of Psychiatry Research. It focused on the echogenicity of the brain stem raphe in patients with several different depressive disorders and these patients' treatment history.

The research builds on findings from as far back as 1994 using transcranial ultrasound to show reduced echogenicity in the brain stem raphe of patients with major depression. So far, no evidence suggests that imaging can be used to differentiate one depressive disorder from another, but the researchers did find correlations with treatment sensitivity.

Walter and colleagues examined 15 patients with single episodes of major depressive disorder, 22 with recurrent major depressive disorder, 15 with adjustment disorder with depressed mood, and 50 healthy controls. They found reduced brain stem echogenicity in all groups, but incidence in the control group was only 8%.

Incidence in patients with single episodes of major depressive disorder was 53%, however, 50% in patients with recurring major depressive disorder, and 60% in patients with adjustment disorder with depressed mood.

The differences showed up among depressed patients when treatment history was correlated with ultrasound exams. Reduced echogenicity in the brain stem raphe had a positive predictive value of 88% for responding well to treatment with serotonin reuptake inhibitors, with a specificity of 88% and sensitivity of 70%.

The second study examined the midbrain of depressed patients, looking for hyperechogenic substantia nigra, thought to indicate a subclinical problem with dopamine processes in that region. It's found in 10% of the general population and is considered a risk marker for Parkinson's disease.

Walter's group did transcranial ultrasound exams on 200 patients, including 55 controls with no depression and no Parkinson's disease. Hyperechogenic substantia nigra was found in 13% of the control group but 87% of the 45 patients with both Parkinson's disease and depression.

There were 55 patients with depression but no diagnosed Parkinson's disease, and 40% of them had hyperechogenic substantia nigra. Of the 45 patients with Parkinson's disease but no depression, 69% showed the sign.

Many patients also showed reduced echogenicity of the brain stem raphe, which showed up more frequently in patients with depression. In patients with Parkinson's disease, however, having both these ultrasound findings was associated with a history of depression prior to disease onset. In patients having depression but no Parkinson's, the combination was associated with motor asymmetry.

Among the 12 patients with depression prior to onset of Parkinson's disease, larger substantia nigra echogenic size correlated with younger disease onset. The authors concluded that transcranial ultrasound could be used to assess an individual's risk for developing Parkinson's disease.