Mania associated with lower dopamine transporter density in bipolar patients

Mania was associated with reduced dopamine transporter density levels among those with bipolar disorder, researchers reported in JAMA Psychiatry.

Lakshmi N. Yatham, MBBS, head of the department of psychiatry at the University of British Columbia, and colleagues sought to assess dopamine transporter (DAT) density in the striatum of the brain in patients with bipolar disorder (BD) with current and recently remitted mania compared with healthy controls.

According to the authors, although dopamine is implicated in the pathophysiology of BD, precise alterations in the dopaminergic system are unknown.

Yatham and colleagues conducted a cross-sectional study in a tertiary care referral center for mood disorders in Vancouver, British Columbia. Forty-seven participants (mean age, 37.8 years; 57.4% female) were included, with 26 with BD (nine with current mania, 17 with recently remitted mania) and 21 matched healthy controls.

The authors measured DAT density through PET scans with [¹¹C]d-threo-methylphenidate (MP). Differences in non-displaceable binding potential (BPND) for DAT was assessed using statistical parametric mapping. Manic symptom severity was measured with the Young Mania Rating Scale (YMRS)

Yatham and colleagues reported MP BPND was significantly lower in participants with BD in the right putamen and nucleus accumbens (mean reduction = 22%), as well as the left putamen and caudate (MR = 24%).

In addition, the reduction in BPND was more extensive and pronounced in patients with current mania, while patients with recently remitted mania had lower BPND in the left striatum but not the right.

Also, there was a significant negative correlation between YMRS scores and MP BPND in the right striatum in patients with current mania (–0.93; 95% CI, –0.99 to –0.69) and those with recently remitted mania (–0.64; 95% CI, –0.86 to –0.23), but not in the left striatum in either group.

“The results showed that patients with BD had a lower MP BPND in the right putamen and nucleus accumbens as well as left putamen and caudate,” Yatham and colleagues wrote. “The reduction in MP BPND was more extensive in patients with current mania and included right putamen, nucleus accumbens and caudate as well as the left putamen, nucleus accumbens and caudate compared not only with healthy control individuals but also patients with recently remitted mania.”