A study out of Bangalore, India suggests that siblings of patients with bipolar disorder show deficits in executive functions and memory even though they do not carry the same diagnosis.

YC Janardhan Reddy of the National Institute of Mental Health and Neurosciences in Bangalore, India and a team of researchers noted that impairments have been reported in relatives of patients with bipolar disorder in previous studies, but the results were inconclusive.

The team set out to compare the neuropsychological performance in siblings with a family history of bipolar disorder to that of individually-matched healthy controls.

“These deficits are consistent with the proposed neurobiological model of bipolar disorder involving the frontotemporal and subcortical circuits,” Reddy and team wrote, pointing to potential endophenotypes for genetic studies.

A psychiatric concept, endophenotype is a kind of biomarker that divides behavioral symptoms into more stable phenotypes with a clear genetic connection.

An evaluation was conducted of 30 unaffected siblings of patients with bipolar disorder against 30 healthy individuals who did not have a family history of the disorder.

The analysis included tests of attention, executive function and memory, and the participants — all between the ages of 18 and 45 — were matched with respect to gender, age and education.

According to researchers, the unaffected siblings performed poorly on the Tower of London test (TOL), the Rey’s auditory verbal learning test (RAVLT), and the Rey’s complex figure test. No significant differences were found between the groups on tests of attention.

With respect to the Tower of London test, which is an indicator of planning ability, unaffected siblings had scores of 80.43 compared to 63.63 for the control group.

The recorded results of the Rey’s auditory verbal learning test were 53.70 for unaffected siblings compared to control group scores of 61.60, and the results of the Rey’s Complex Figure Test were also poorer for unaffected siblings but not significantly.

The team added that “future studies could couple cognitive and imaging strategies and genomics to identify neurocognitive endophenotypes in bipolar disorder.”

A serious mental illness, bipolar disorder is estimated to affect 5.7 million adults in the U.S. and is characterized by extreme mood changes running the gamut from mania to depression. Risky behaviors are associated with bipolar disorder, and it often causes damage to family relationships and careers, and even suicidal tendencies if not treated.

Findings of this study can be found in the journal Bipolar Disorders.

Source: Bipolar Disorders