Bipolar disorder may affect the brains of men and women in different ways.
The effect of the illness on memory, according to one recent study, is more severe in men.
Dr. Sophia Frangou, of the section of Neurobiology of Psychosis, at the Institute of Psychiatry, King’s College in London, and her colleagues found that compared to women, men with bipolar disorder type I had more difficulty performing on tests of immediate memory, as well as auditory and visual memory.
Bipolar disorder is a serious mood disorder that affects nearly 5 million Americans. In addition to the classic symptoms of cycling between periods of ‘low’ (depressed) mood and ‘high’ (manic or hypomanic) the illness can have severe effects on one’s personal life, family, career goals, physical health, overall life functioning, and survival. More than 20 percent, according to some data, commit suicide. Many studies have shown negative effects of the illness on cognition, and although the exact cause is difficult to ascertain, clearly untreated illness can cause cognitive defects, as can certain medications or treatments.
To analyze the effect of gender on cognition in bipolar patients, Frangou and her colleagues enrolled 132 patients in the study. 86 patients had bipolar I (a subtype of bipolar disorder characterized by more extreme mania); this group included 36 bipolar men and 50 women with the disorder. 46 healthy controls were included (21 men and 25 women.) All of the patients with bipolar I disorder were similar in age of onset, duration of illness, number of episodes or hospitalizations, and global assessment of functioning (GAF) scores.
All study participants were asked to complete a variety of tests to assess cognitive function, including tasks to measure general intellectual ability, memory encoding, recognition, retrieval, response inhibition, and executive function (abstraction and perseveration). Bipolar illness’s effect on patients’ daily lives was assessed using the global assessment of functioning (GAF) scale.
The team found that there was a difference in the test results of the men compared both to the women with bipolar illness and to the healthy individuals. The cognitive defects were noted particularly in the areas of immediate memory (similar to short-term memory), encoding, and retrieval processes. (Memory encoding is the ability to store new memories.)
Furthermore, in the men, there was a statistically significant association between a decreased immediate memory function and an overall decreased global assessment of functioning score, which indicates that the more severely affected men with bipolar I would have a harder time in their daily function.
There were no apparent differences in general intellectual function, the ability to form concepts, perseverence, or the ability to appropriately inhibit a response.
“Our results support the notion that gender may modulate the degree of immediate memory dysfunction in bipolar disorder and its impact on overall level of function,” says Frangou.
Previous studies have shown that gender plays a role in the clinical course and severity of bipolar disorder, and these results shed some light on one pathway by which such a decline in function may occur. In addition to deciphering why men are more severely affected in this area, with the ultimate goal of a novel therapy, future research may be able to help further define precisely where memory deficits occur, and allow for development of targeted treatments. Perhaps occupational or other therapy designed to improve memory function might result in improved global functional outcome in severely affected men.
Dr. Frangou’s results can be found in the journal Psychological Medicine.
Source: Psychological Medicine