Cognitive deficits in first-degree relatives of bipolar patients: the use of homogeneous subgroups in the search of cognitive endophenotypes

Abstract

Previous studies have demonstrated impairments in attention, memory and executive functions in euthymic bipolar patients (BP) as well as their unaffected first-degree relatives, albeit in an attenuated form. Subsequently, cognitive deficits are discussed as a possible endophenotype of bipolar disorder. However, recent studies showed that only a subgroup of BP shows cognitive impairments. The aim of the present study was to investigate cognitive functioning in relatives compared to BP, to find out if the differentiation in a cognitive deficit vs. non-deficit subgroup is valid for relatives of BP, too. Therefore, the performance of 27 unaffected relatives of BP, 27 euthymic BP and 27 HC were compared using a neuropsychological test battery. The results showed that BP exhibited a reduced psychomotor speed and deficits in working memory compared to relatives and HC. Relatives performed significantly slower (psychomotor speed) as compared to HC (p = 0.024); performance in the other test measures lie between BP and HC. Furthermore, a detailed evaluation of the data indicated that only subgroups of BP and relatives exhibited cognitive impairments in the implemented tests. However, the deficit and non-deficit groups did not differ in sociodemographic and clinical variables from each other, possibly due to the small sample size. In conclusion, our results suggest that reduced psychomotor speed could serve as a potential endophenotype for bipolar disorder which should be investigated along the developmental trajectory of this disorder, also to examine whether abnormalities therein precede onset of the first mood episode. Furthermore, the division of relatives into subgroups aids in the identification of stable trait markers and high-risk bipolar groups and could enable early prevention strategies. As to that more research using distinct and homogeneous subgroups is necessary.

Neurocognitive performance as an endophenotype for mood disorder subgroups

“…Indeed, several authors have suggested that similar to genetic and other biologic findings (Lichtenstein et al, 2009), BPD with psychotic features is more closely affiliated with schizophrenia (Tondo et al, 2016). These and other correlates of cognitive performance have been increasingly used to identify subtypes of BPD (Volkert et al, 2016). …”

“…Most participants in studies of neurocognitive endophenotypes for mood disorder subgroups have been recruited in clinical settings that represent the most severe cases (Bora et al, 2009; Volkert et al, 2016), often during the acute phase of mood disorders that may be complicated by affective state and medication use (Burdick et al, 2014; de Brito Ferreira Fernandes et al, 2016; Georgiades et al, 2016; Glahn et al, 2010; Lee et al, 2014; Xu et al, 2012). Associations found in these studies differ by source of the samples, mood disorder subgroups (Godard et al, 2011), clinical characteristics including current state (Martinez-Aran et al, 2004), medication use, psychotic features, severity, consequences (Jaeger et al, 2006; Martinez-Aran et al, 2007; Ruggero et al, 2007) or precursors of the disorder (Pavuluri et al, 2006), as well as substantial differences in the measures and domains assessed (Porter et al, 2015).…”

Theory of mind and executive functions in bipolar disorder patients and their first-degree relatives (tur)

“…Yapılan çalışmalarda BB olan hastalar ve yakınlarında çeşitli bilişsel bozukluklar olduğu görülmüştür (4,5). Her ne kadar literatürde hasta yakınları ile kontroller arasında anlamlı fark saptamayan çalışmalar olsa da (6); BB olan hastalar ve yakınları arasında özellikle yanıt inhibisyonu ve planlama gibi yürütücü işlevler, sözel öğrenme, sözel bellek ve sözel çalışan bellek açısından benzerlik olduğu, bu işlev bozukluklarının BB için endofenotip adayı olabileceğini öne süren metaanaliz çalışmaları mevcuttur (7).…”

Executive Function Is Selectively Impaired in Old Age Bipolar Depression

“…This issue is relevant because cognitive impairment can produce an additional impact on the already compromised functionality of elderly with BD ( Rise et al, 2016 ). Besides that, the identification of specific cognitive profiles in BD can perhaps help differentiate subgroups and pave the way to the identification of possible endophenotypes ( Volkert et al, 2016 ). Finally, a comprehensive mapping of cognitive domains impaired in BD can add some insights into the physiopathology of the disorder and the many mechanisms by which cognitive symptoms may relate to behavior alterations.…”