Bipolar disorder (BD) is a chronic mental health condition characterized by significant mood swings including emotional highs (mania or hypomania) and lows (depression). This disorder impacts several areas of cognitive and functional performance, with an increased prevalence of sleep disturbances observed in this demographic. In the elderly, these manifestations could potentially exacerbate cognitive decline, an area that remains underexplored.

Research indicates that nearly 60% of patients with bipolar disorder suffer from some form of sleep disturbance, which can range from insomnia and poor sleep quality to irregular sleep-wake cycles De la Fuente-Tomás L et al.(2018)^[1]. This is particularly concerning as sleep plays a critical role in cognitive processing and emotional regulation O'Rourke N et al.(2021)^[2]. Moreover, cognitive dysfunction in bipolar disorder has been associated with deficits in memory, executive function, and attention Fekih-Romdhane F et al.(2020)^[3], which may be further impacted by poor sleep.

The interrelationship between sleep and cognitive function is particularly pronounced in the elderly, where natural degenerative processes are compounded by mental health issues such as bipolar disorder. Studies such as those by Kanady JC et al.(2017)^[4] have shown that disrupted sleep may accelerate cognitive decline in older adults. However, the specific impact of sleep quality on cognitive function in elderly bipolar patients has not been extensively studied, leaving a gap in tailored management strategies for this population.

Recent reviews Slyepchenko A et al.(2019)^[5] highlight the need for targeted research that addresses the intersection of aging, bipolar disorder, and sleep-related cognitive impairment. Such studies could provide insights into potential therapeutic targets and interventions designed to improve outcomes in this vulnerable group.

Aim

To explore the relationship between sleep quality and cognitive function in elderly patients diagnosed with bipolar disorder.

 Objectives

1. To assess the quality of sleep in elderly bipolar disorder patients and its direct correlation with cognitive performance.
2. To determine specific cognitive domains most affected by the variability in sleep quality in this population.

Source of Data: Data was obtained from elderly patients diagnosed with bipolar disorder attending the psychiatric outpatient department at a tertiary care center.

Study Design: A cross-sectional study design was utilized to assess the relationship between sleep quality and cognitive function.

Study Location: The study was conducted at the Geriatric Psychiatry unit at tertiary care hospital.

Study Duration: Data collection spanned from January 2024 to December 2024.

Sample Size: The study comprised 200 elderly patients with bipolar disorder.

Inclusion Criteria: Participants included were those aged 60 years and above, diagnosed with bipolar disorder according to the DSM-5 criteria, able to provide informed consent, and able to complete sleep quality and cognitive function assessments.

Exclusion Criteria: Excluded were patients with neurodegenerative diseases like Alzheimer’s or Parkinson’s, those with severe sensory deficits that could impede testing, or severe psychiatric conditions other than bipolar disorder that might affect cognitive assessment.

Procedure and Methodology: Participants underwent a structured clinical interview to confirm the diagnosis and gather demographic data. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), and cognitive function was measured through standardized neuropsychological tests covering memory, executive function, and attention.

Sample Processing: No biological samples were processed as this study focused on psychological assessments.

Statistical Methods: Data were analyzed using SPSS software. Descriptive statistics summarized demographics, sleep quality, and cognitive scores. Correlation analyses and multiple regression models determined the impact of sleep quality on cognitive function.

Data Collection: Data were collected through face-to-face interviews and self-administered questionnaires during scheduled visits to the psychiatric outpatient department

Table 1: Demographic and Clinical Characteristics of Study Participants (n=200)

Table 1 presents the demographic and clinical characteristics of the 200 study participants involved in examining the relationship between sleep quality and cognitive function in elderly patients with bipolar disorder. The average age of participants was 68.4 years with a standard deviation of 7.2 years, highlighting a senior cohort. Gender distribution showed a higher proportion of females (56.5%) compared to males (43.5%). Participants had lived with bipolar disorder for an average of 10.3 years. The average score on the Pittsburgh Sleep Quality Index was 9.7, indicating poor sleep quality among the group, and the overall cognitive score was 82.1, suggesting varied cognitive function across the sample.

Table 2: Sleep Quality and Its Correlation with Cognitive Performance

Table 2 delves into the specifics of sleep quality and its correlation with cognitive performance. Key findings include a negative correlation between total sleep time (average 6.2 hours) and cognitive performance (r = -0.47), indicating that reduced sleep time is associated with poorer cognitive outcomes. Sleep efficiency stood at 78.3% on average, with a stronger negative correlation (r = -0.52) suggesting that higher sleep efficiency relates to better cognitive performance. Sleep latency and the number of awakenings also showed significant positive correlations with cognitive performance, while daytime dysfunction was significantly linked to poorer cognitive function.

Table 3: Cognitive Domains Affected by Variability in Sleep Quality

Table 3 focuses on the impact of sleep quality on specific cognitive domains. It was found that all assessed cognitive domains—memory, executive function, attention, language skills, and visuospatial ability—exhibited significant negative correlations with variability in sleep quality. Memory, with a mean score of 24.1 and a correlation coefficient of -0.38, and executive function, with a mean score of 30.2 and a correlation coefficient of -0.42, were particularly affected. This suggests that poorer sleep quality notably impairs these cognitive domains in elderly bipolar disorder patients.

Table 1: Demographic and Clinical Characteristics The demographic breakdown of the study participants, with an average age of 68.4 years, aligns with research that emphasizes the increased vulnerability of the elderly to both cognitive decline and sleep disturbances Pearson O et al.(2023)^[6]. The near-equal distribution of genders (56.5% female, 43.5% male) provides a balanced perspective that is essential for assessing gender-specific responses, which previous studies have indicated may differ due to hormonal and physiological variations Laskemoen JF et al.(2020)^[7]. The average duration of bipolar disorder in this cohort was 10.3 years, emphasizing chronic exposure to the potential cognitive wear-and-tear associated with the disorder. This cohort's mean Pittsburgh Sleep Quality Index (PSQI) score of 9.7 suggests significant sleep disturbances, a common issue in bipolar disorder that has been linked to poorer cognitive outcomes Ahmadpanah M et al.(2022)^[8].

 Table 2: Sleep Quality and Its Correlation with Cognitive Performance This table reveals significant correlations between various aspects of sleep quality and cognitive performance. Notably, total sleep time and sleep efficiency both showed strong negative correlations with cognitive performance, suggesting that decreased sleep quantity and quality are associated with lower cognitive functioning. This is consistent with findings from Guan Q et al.(2020)^[9], who noted that sleep efficiency is a critical predictor of cognitive decline in the elderly. Furthermore, the positive correlations between sleep latency and the number of awakenings with poorer cognitive performance reinforce the notion that interrupted and delayed sleep can exacerbate cognitive deficits, supporting the conclusions drawn by Geoffroy PA et al.(2016)^[10].

 Table 3: Cognitive Domains Affected by Variability in Sleep Quality The cognitive testing results indicate that all measured cognitive domains are negatively impacted by poor sleep quality, with significant correlations across memory, executive function, attention, language skills, and visuospatial abilities. These findings resonate with those of Cipriani G et al.(2017)^[11], who found that sleep disturbances particularly affect memory and executive functions in bipolar disorder patients. The strongest correlation was observed in executive functions, highlighting the critical impact of sleep on higher-order cognitive processes that are crucial for daily functioning

The study "The Relationship Between Sleep Quality and Cognitive Function in Elderly Patients with Bipolar Disorder: A Cross-Sectional Approach" provides valuable insights into the significant impact of sleep disturbances on the cognitive health of elderly individuals diagnosed with bipolar disorder. Our findings underscore the critical role that sleep quality plays in maintaining cognitive functions, particularly in an aging population vulnerable to both psychiatric and neurocognitive disorders.

The analysis revealed that diminished sleep quality, characterized by reduced total sleep time and sleep efficiency, was strongly associated with declines in various cognitive domains, including memory, executive function, attention, language skills, and visuospatial abilities. These results are in line with existing literature, which highlights the complex interactions between sleep and cognitive processes, especially in the context of psychiatric conditions like bipolar disorder.

Moreover, the study identified specific aspects of sleep disruption—such as increased sleep latency and frequent awakenings—that contribute to poorer cognitive outcomes. These disturbances not only exacerbate the cognitive deficits commonly associated with bipolar disorder but also complicate the clinical management of these patients.

Given the strong correlation between poor sleep and reduced cognitive function, our study highlights the necessity for clinicians to prioritize the assessment and treatment of sleep disorders in this demographic. Integrative approaches that combine psychiatric care with sleep management may offer the most beneficial outcomes, potentially stabilizing mood and enhancing cognitive function.

1. Cross-Sectional Design: One of the primary limitations of this study is its cross-sectional nature, which restricts the ability to infer causality between sleep quality and cognitive function. While significant associations were observed, it is not possible to determine whether poor sleep quality causes cognitive decline, if cognitive decline contributes to worse sleep, or if both are influenced by another underlying factor.
2. Lack of Objective Sleep Measures: The study relied heavily on subjective reports of sleep quality via the Pittsburgh Sleep Quality Index. This method may introduce self-report bias and does not capture detailed information about sleep architecture that could be obtained through objective measures such as polysomnography or actigraphy.
3. Generalizability: The findings are based on a specific population of elderly patients with bipolar disorder, which may not be generalizable to younger populations or those with different psychiatric or neurological conditions. Additionally, the study setting in a tertiary care center might attract patients with more severe or treatment-resistant forms of bipolar disorder, potentially skewing the results.
4. Control of Confounding Variables: Although the study controlled for basic demographic variables, there are many potential confounders that were not accounted for, such as medication use (especially psychotropics that affect sleep and cognition), comorbid health conditions, lifestyle factors (e.g., diet, physical activity), and social determinants of health, which could significantly influence both sleep quality and cognitive function.
5. Sample Size and Power: The sample size of 200 participants, while adequate for detecting some statistical differences, may not have been large enough to explore more nuanced aspects of the relationship between sleep and cognitive domains or to conduct subgroup analyses (e.g., based on severity of mood symptoms, type of bipolar disorder, or treatment regimens).
6. Cognitive Assessment Tools: The tools used to assess cognitive function might not have captured all relevant aspects of cognitive health in this population. More comprehensive neuropsychological batteries could provide a deeper understanding of cognitive deficits associated with both bipolar disorder and sleep disturbances.
7. Follow-up Duration: As a cross-sectional study, it lacks follow-up data which would be valuable to understand the long-term effects of sleep quality on cognitive decline in this population. Longitudinal studies could provide more definitive information on the trajectory of cognitive changes over time in relation to sleep patterns.

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