Cognitive Impairment In Manic Bipolar Patients: Important, Understated, Significant Aspects
Compared with healthy individuals, patients with bipolar I disorder (BD I) experience cognitive deficits, including impairment of sustained attention, memory, and executive function. These deficits have been observed in all phases of illness, including euthymia. Deficits in cognitive function may be associated with illness severity, current state (manic, depressive, euthymic, or mixed), and polarity of previous episodes. Clinical assessments of cognitive function should be applied to assess the stability or evolution of cognitive impairment over time.
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The following is a summary of Vrabie M, Marinescu V, Talaşman A, Tăutu O, Drima E, Micluţia I. Cognitive impairment in manic bipolar patients: important, understated, significant aspects. Ann Gen Psychiatry. 2015;14:41, which was developed independently of the article authors.
- Patients with bipolar disorder (BD) experience impairment of sustained attention, memory, executive function, and other aspects of cognition.
- Cognitive impairment occurs during acute illness and may persist throughout periods of euthymia despite pharmacologic intervention.
- Previous research has demonstrated a positive correlation between impairment of verbal memory and duration of illness, number of past manic episodes, and number of psychiatric hospitalizations, suggesting that illness severity may negatively affect cognitive function.
- This study evaluated cognitive deterioration in patients with BD I and assessed correlations between cognitive impairment and the course of bipolar illness, as described by the number of hospitalizations, duration of illness, age at onset of illness, and predominant polarity of previous episodes.
- Cognitive function was assessed in adults with BD I (n=137) and healthy controls (n=62) matched for age, gender, and level of education.
- Domains of cognitive function assessed included those consistently impaired and related to outcome in BD: verbal memory, working memory, psychomotor speed, attention and speed of information processing, executive function, and verbal fluency.
- Subgroup analyses of cognitive function were performed among patients with BD I experiencing manic, depressive, euthymic, and mixed episodes; course of illness was assessed retrospectively.
- Patients with BD I and healthy controls were evenly matched in terms of age, education, and gender.
- Patients with BD I:
- Experienced a median of 11 hospitalizations
- Achieved significantly lower scores on all tests of cognitive function compared with the control group (Figure 1)
- When subgroups of patients with BD I were compared, differences were noted in cognitive function test scores among all groups (Figure 2).
- Several correlations were observed between course of illness and cognitive function:
- The strongest correlations overall were:
- Age at onset of illness and verbal fluency scores
- Duration of illness and psychomotor speed scores
- Number of hospitalizations and verbal or working memory scores
- In the manic subgroup, verbal memory scores were:
- Positively correlated with age at onset of illness
- Negatively correlated with duration of illness and number of hospitalizations
- In the depressive subgroup:
- Verbal fluency scores were positively correlated with age at onset of illness.
- Working memory scores were negatively correlated with both duration of illness and number of hospitalizations.
- In both the euthymic and the mixed episodes subgroups, attention and speed of information processing showed a significant negative correlation with duration of illness and number of hospitalizations.
- The strongest correlations overall were:
- Compared with patients who experienced mainly depressive episodes, patients who experienced mainly manic episodes had significantly lower scores across several cognitive functions: verbal memory, working memory, attention and speed of information processing, and executive function/reasoning, and problem solving.
Conclusions & Clinical Implications
- Patients with BD I performed more poorly than healthy individuals on all aspects of cognitive function tested.
- A more severe course of illness, as defined by a higher number of past hospitalizations, earlier age at onset of illness, and longer duration of illness, may contribute to the extent of cognitive decline seen in BD I.
- Deficits in cognitive function were associated with current state (ie, manic, depressive, euthymic, or mixed) and the polarity of previous episodes.
- Cognitive deterioration (eg, impaired verbal memory, working memory, psychomotor speed, and verbal fluency) in patients with bipolar I disorder correlated with illness severity.
- Because of the diversity in cognitive impairment among patients with different episode types, rehabilitation programs should be tailored according to individual patients’ needs.
- Clinical assessments of cognitive function should be applied to determine the stability or evolution of cognitive impairment over time in patients with bipolar I disorder.
This summary has been developed independently of the authors. VM was a speaker for AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Janssen, Lundbeck, Organon, Pfizer, Sanofi-Aventis, and Servier; participated in clinical research funded by AstraZeneca, Corcept, Eli Lilly, Gedeon Richter, Janssen, Pfizer, Roche, Sanofi-Aventis, Servier; and was a member of an advisory board for Eli Lilly, Janssen, Lundbeck, and Roche. MV, AT, OT, and ED have no competing interests. IM received honoraria as a coordinating and principal investigator of the EUFEST study and several studies led by CliniRx, Galenica, Otsuka, Pierre Fabre, and Quintiles and was a national coordinator of e-STAR and the PASTEL study from Johnson & Johnson. She is a consultant or member on advisory boards for AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Johnson & Johnson, and Lundbeck and is a speaker for Angelini, AstraZeneca, Bristol-Myers Squibb, Eli Lilly, EVER Pharma, Glenmark, Lundbeck, Novartis, Pfizer, Sanofi, Servier, Terapia, Torrent, and Zentiva.