Individuals with bipolar disorder (BD) have a higher incidence of Parkinson disease (PD), according to the results of a study published in Neurology. In addition, more frequent manic/mixed and depressive episodes increase this risk...

The study found that those with BD had a higher incidence of PD and a shorter duration from enrollment to diagnosis of PD than control individuals during the follow-up period (0.7% vs 0.1%). Patients with a higher frequency of psychiatric admission for BD had an increased risk of developing PD compared with those admitted less than once per year. The hazard ratio for developing PD for 1 to 2 manic/mixed episodes per year was 4.02, whereas for 1 to 2 depressive episodes per year, it was 2.67. For more than 2 episodes per year, the hazard ratios were 6.29 for manic/mixed and 6.19 for depressive.

Until defining characteristics were established almost 40 years ago in the DSM-III, Borderline Personality Disorder (BPD) was a vague and ambiguous concept. Because a primary characteristic is mood swings, some early researchers insisted BPD was merely a variation of Bipolar Affective Disorder (BAD). After all, if there could be Bipolar I and Bipolar II, why wasn't so-called Borderline Personality Disorder something along the line of Bipolar IV, V, or VI? ...

​Researchers discovered similarities and differences in metabolism in these two groups. Both groups, compared to controls, exhibited decreased metabolism in parts of the brain related to emotional control and social interactions. BAD II patients exhibited distinctly decreased metabolism in the cerebellum, brain stem, and parts of the cortex associated in other studies with neurobiological depression. BPD patients showed lower metabolism in other areas including the hypothalamus. The hypothalamus is intimately associated with the endocrine system, which involves stress responses and hormone secretions including cortisol, testosterone, and estrogen. The hypothalamus is also key in the production of oxytocin, which is related to maternal feelings and warm social behavior.