New Study Reveals Cognitive Impairments in Bipolar Disorder Develop Gradually
A recent study conducted in Canada has shed light on the development of cognitive impairments in individuals with bipolar disorder. The study, published in Psychological Medicine, aimed to determine whether these impairments develop early with the onset of the disorder or gradually over time through “accelerated aging.”
Bipolar disorder is a mental health condition characterized by extreme mood swings, including periods of intense mania and deep depression. These mood episodes can range in intensity and duration, significantly disrupting daily life. It is estimated that bipolar disorder affects approximately 1-2% of the population.
Previous research has shown that individuals with bipolar disorder also experience impairments in various cognitive domains compared to healthy individuals. These impairments tend to be particularly pronounced during depressive episodes but persist to some degree even during periods of balanced mood. They also appear to be more severe in older individuals.
Study author Brett D. M. Jones and his colleagues aimed to investigate how these cognitive impairments develop. They considered three possibilities: cognitive impairment starting early and persisting as individuals age (“early hit” hypothesis), cognitive abilities declining faster with age in individuals with bipolar disorder leading to accelerated aging effects (“accelerated aging” hypothesis), or a combination of both factors being at play.
To investigate these possibilities, the researchers compared the cognitive performance of individuals with bipolar disorder of different ages to that of healthy individuals. The data came from four studies conducted at the Centre for Addiction and Mental Health in Toronto, Canada.
The participants were divided into four groups: younger individuals with bipolar disorder (up to 49 years old), older individuals with bipolar disorder (50 years and above), healthy individuals up to 49 years old, and healthy individuals 50 years and above. All participants completed a battery of neuropsychological assessments to evaluate various cognitive domains.
The results showed that younger participants with bipolar disorder developed the condition at an average age of 19, while older participants developed it at an average age of 30. Participants with bipolar disorder experienced three times more depressive episodes than manic episodes. Before the onset of bipolar disorder, their intelligence levels were similar to those of healthy participants.
When comparing cognitive performance, participants with bipolar disorder performed worse than healthy individuals of the same age on most cognitive tests, with the differences being more pronounced in the older groups.
After analyzing the data, the researchers found that differences in attention, processing speed, and executive function between younger individuals with and without bipolar disorder supported the accelerated aging hypothesis. The gap in cognitive performance between these groups increased with age. On the other hand, differences in verbal memory supported the “early hit” hypothesis, indicating that verbal memory impairments developed quickly with the onset of bipolar disorder.
The study authors concluded that there is evidence to support the concept of accelerated aging in individuals with bipolar disorder in certain cognitive domains. However, they also noted limitations in the study, such as its cross-sectional design, which does not allow for any cause-and-effect conclusions.
This study provides valuable insights into the cognitive functioning of individuals with bipolar disorder. Understanding the development of cognitive impairments in this population can help inform treatment approaches and interventions to improve their overall quality of life.