Is there an association between subjective and objective measures of cognitive function in patients with affective disorders?

Svendsen AM, Kessing LV, Munkholm K, Vinberg M, Miskowiak KW

Nord J Psychiatry. 2012 Sep;66(4):248-53.

Abstract

BACKGROUND: Patients with affective disorders experience cognitive dysfunction in addition to their affective symptoms. The relationship between subjectively experienced and objectively measured cognitive function is controversial with several studies reporting no correlation between subjective and objective deficits.

AIMS: To investigate whether there is a correlation between subjectively reported and objectively measured cognitive function in patients with affective disorders, and whether subjective complaints predict objectively measured dysfunction.

METHODS: The study included 45 participants; 15 with bipolar disorder (BD), 15 with unipolar disorder (UD) and 15 healthy individuals. Participants’ subjectively experienced cognitive function and objective cognitive function were assessed with the Massachusetts General Hospital Cognitive and Physical Functioning Questionnaire (CPFQ) and the Screen for Cognitive Impairment in Psychiatry (SCIP), respectively. Patients were rated for affective symptoms with Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS).

RESULTS: Patients demonstrated subjective and objective cognitive dysfunction relative to controls (P-values ≤ 0.01) but there were no differences between patient groups (P > 0.1). We found no correlation between subjectively experienced and objectively measured cognitive dysfunction in BD (P = 0.7), and a non-significant trend towards a correlation in UD (P = 0.06), which disappeared when controlling for gender (P = 0.1).

CONCLUSION: Our results suggest that it is not necessarily patients who have cognitive complaints that are most impaired. If confirmed in a larger sample, our findings suggest that neuropsychological assessment is warranted to elucidate the potential role of cognitive dysfunction in patients’ everyday lives and to inform treatment strategies targeting these difficulties.

Is there a difference in subjective experience of cognitive function in patients with unipolar disorder versus bipolar disorder?

Miskowiak K, Vinberg M, Christensen EM, Kessing LV

Nord J Psychiatry. 2012 Dec;66(6):389-95.

Abstract

BACKGROUND: Cognitive dysfunction in unipolar disorder (UD) and bipolar disorder (BD) may persist into remission and affect psychosocial function. Executive and memory deficits during remission may be more pronounced in BD than UD. However, patients’ subjective experience of cognitive difficulties is poorly understood, and it is unclear whether BD and UD patients experience different cognitive difficulties.

AIMS: To investigate whether there are differences in the quality and magnitude of subjective cognitive difficulties between UD and BD, and which factors influence the subjective cognitive difficulties in these patients.

METHODS: Patients with BD (n = 54) or UD (n = 45) were referred to the outpatient mood disorder clinic at Department of Psychiatry, Copenhagen University Hospital, following hospital discharge. Affective symptoms and patients’ experience of cognitive symptoms were assessed at their initial consultation at the clinic.

RESULTS: Patients experienced mild to moderate cognitive impairment despite being in partial or full remission, but there were no differences in subjective difficulties between BD and UD. Subjective cognitive dysfunction was predicted by depression severity, anxiety and mania symptoms rather than by diagnosis, age, gender or alcohol misuse.

CONCLUSION: The absence of difference in subjective cognitive difficulties between UD and BD contrasts with evidence of greater objective dysfunction in BD. This highlights a potential discord between subjective and objective measures of cognitive function. Subjective cognitive function was predicted by affective symptoms, perhaps suggesting that this reflects mood symptoms rather than objective deficits. This points to a clinical need for objective assessment of cognitive function in these patient groups.