Recurrent manic episodes reduce cognitive performance in bipolar disorder
MedWire News: Recurrent manic episodes are associated with progressive worsening of cognitive performance in patients with bipolar I disorder (BD-I), research suggests.
"If the hypothesis suggested by the current study is verified (namely, that manic relapse may cause cognitive decline), the importance of early intervention and good treatment adherence becomes not only a matter of symptom control but a potentially important intervention to protect against functional decline," comment Carlos López-Jaramillo (University of Antioquia, Medellín, Colombia) and team.
The researchers enrolled 98 euthymic BD-1 patients and 66 mentally healthy individuals (controls) who were aged between 18 and 60 years.
Of the BD-I patients, 24 had experienced one manic episode, 27 had experienced two episodes, and 47 had experienced three or more manic episodes.
All of the patients underwent a neuropsychological test battery to assess attention, executive function, memory (verbal, visual, and working), psychomotor speed, and intellectual capacity.
Compared with controls, patients with one previous manic episode showed a significant deficit only in working memory.
Patients with two manic episodes showed greater cognitive impairments compared with controls, with deficits in working memory, short-term visuo-verbal episodic memory with semantic association, logical memory recognition, and phonological verbal fluency, as well as delayed recall.
Patients with at least three previous manic episodes had the worst cognitive performance compared with controls, demonstrating deficits in short-term visuo-verbal episodic memory with semantic association, long-term recall, logical memory recognition, and several executive function-related measures, including semantic verbal fluency, phonological verbal fluency, execution time, and error rate. This group also showed psychomotor slowing in tests of executive attention, compared with controls.
Overall, the number of manic episodes was positively associated with poorer performance on the neurocognitive tests, even after accounting for episodes of depression, disease chronicity, age at onset, and medication use.
López-Jaramillo and team conclude in the journal Bipolar Disorders: "The number of manic episodes predicted poor cognitive performance, suggesting that the recurrence of mania may have a long-term neuropsychological impact."
They add: "Prospective follow-up studies need to be completed to explore this effect further as better treatment adherence may have a protective effect on neurocognitive function."
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By Mark Cowen