Cognitive-linguistic deficits in euthymic elderly patients with bipolar disorder

Abstract

Background: There is increasing evidence that bipolar disorder is also associated with neuropsychological impairments persisting during euthymia, thus representing a trait-like feature of the disease. Language and speech abnormalities are also present in bipolar disorder, especially in verbal fluency and verbal memory. However, there is a lack of studies in the literature investigating different levels of linguistic processing (phonological, syntactical, and semantic) in a single cohort of euthymic bipolar patients. Based on previous Findings of pervasive language impairment in euthymic elderly bipolar patients, the aim of this study was to comprise a more thorough investigation on the subject. Methods: We studied 19 euthymic bipolar patients aged 60 and above, and 20 cognitively healthy subjects using the Arizona Battery for Communication Disorders of Dementia (ABCD) and the Test for Reception of Grammar Version 2 (TROG-2) in order to assess the phonological, syntactic, and semantic domains of language. Results: Bipolar patients performed poorer than controls in Linguistic Expression (p=0.011), in Linguistic Comprehension (Following Commands; p=0.025 and Reading Comprehension of Sentences; p=0.007), and in the TROG-2 (p=0.006). Limitations: The small sample comprising only elderly patients; the lack of statistical power to analyze the potential effect of individual medications on the cognitive performance. Conclusions: Our data demonstrate that linguistic impairment is present in euthymic bipolar patients, affecting mostly syntactic and lexical semantic abilities, both in comprehension and production of language. These deficits are interrelated with other cognitive skills also known to be affected in bipolar disorder, such as executive functions and episodic memory.