Neurocognitive features in subgroups of bipolar disorder

Abstract

ObjectiveTo examine which subgroups of DSM-IV bipolar disorder (BD) [BD type I (BD-I) or BD type II (BD-II), and subgroups based on history of psychosis, presenting polarity, and age at onset] differentiate best regarding neurocognitive measures.MethodsA total of 199 patients with BD were characterized by clinical and neurocognitive features. The distribution of subgroups in this sample was: BD-I, 64% and BD-II, 36%; 60% had a history of psychosis; 57% had depression as the presenting polarity; 61% had an early onset of BD, 25% had a mid onset, and 14% had a late onset. We used multivariate regression analyses to assess relationships between neurocognitive variables and clinical subgroups.ResultsBoth BD-I diagnosis and elevated presenting polarity were related to impairments in verbal memory, with elevated presenting polarity explaining more of the variance in this cognitive domain (22.5%). History of psychosis and BD-I diagnosis were both related to impairment in semantic fluency, with history of psychosis explaining more of the variance (11.6%).ConclusionPoor performance in verbal memory appears to be associated with an elevated presenting polarity, and poor performance in semantic fluency appears to be associated with a lifetime history of psychosis.

Evidence for cognitive subgroups in bipolar disorder and the influence of subclinical depression and sleep disturbances

“…The authors confirmed cognitive impairments in euthymic BP, but found considerably lower effect sizes (d =.26-.63) than previous meta-analyses (d= .5-1). In line with this result, other studies reported that only a part of their bipolar sample had significant cognitive impairments (Altshuler et al, 2004;Aminoff et al, 2013;Iverson et al, 2011;Martino et al, 2008). Thus, there seem to be subgroups within the cluster of BD; however, the underlying reasons are unclear: Some patients do not reach their former level of cognitive performance and become more disabled with progressing illness, while others remit completely after each episode and maintain a high occupational and social functioning (Gilbert and Marwaha, 2013).…”

“…Unfortunately, many previous studies did not report criteria for the duration of euthymic mood in their samples, or did not control for sub-depressive symptoms (Bombin et al, 2013;Ryan et al, 2012;Thompson et al, 2005) which might well account for discrepancies in the published literature. Some investigations reported high depression scores in their samples and therefore included more symptomatic patients, which could be responsible for larger effects (Aminoff et al, 2013;Chaves et al, 2011;Levy et al, 2013). Other studies conducted neuropsychological tests after a very short period of remission, which is still a relatively unstable state (Brissos et al, 2011;Dittmann et al, 2008).…”

“…However, Dittmann et al (2008) and Chaves et al (2011) found no neuropsychological differences between these two diagnosis types. The fact that patients with BD Type-I have full-blown manic episodes and more psychotic symptoms could contribute to these inconsistent findings (Palsson et al, 2013), as some authors found indeed a significant association between psychotic symptoms and cognition (Aminoff et al, 2013;Bora et al, 2011), while others did not (Brissos et al, 2011). Furthermore, individuals diagnosed with BD Type-I are more often treated with antipsychotics compared to BD-II, which could contribute to cognitive impairments in this patient group (Arts et al, 2011;Jamrozinski et al, 2009;Palsson et al, 2013;Torrent et al, 2011).…”

“…Another often reported finding is that patients diagnosed with BD Type-I have more cognitive deficits than patients with BD Type-II (Aminoff et al, 2013;Ancin et al, 2013;Palsson et al, 2013;Torrent et al, 2006). However, Dittmann et al (2008) and Chaves et al (2011) found no neuropsychological differences between these two diagnosis types.…”

“…For instance, significant associations between cognitive deficits and greater number of episodes have been found (Martinez-Aran et al, 2004;Thompson et al, 2005). Furthermore, higher incidences of manic episodes (Aminoff et al, 2013;Bourne et al, 2013;Lopez-Jaramillo et al, 2010), longer duration of disease (Ryan et al, 2012;Torrent et al, 2012), and more hospitalisations were described to be associated with cognitive impairment (Ancin et al, 2013;Ryan et al, 2012). Therefore, some authors suggested that severe mood symptoms could act like stress-induced neurotoxins (Lopez-Jaramillo et al, 2010).…”