Cognitive psychosis impact extends to relatives
medwireNews: The cognitive deficits commonly seen in patients with psychotic disorders are also present in their first-degree relatives, a study shows.
Researchers led by S Kristian Hill (Rosalind Franklin University of Medicine and Science, Chicago, Illinois, USA) found that cognitive impairments generally affected relatives of patients with schizophrenia, but were only present in relatives of patients with psychotic bipolar disorder if they already had psychotic or affective personality traits.
"This pattern suggests that cognitive deficits in families with a schizophrenia proband are transmitted at least partially independently from factors associated with schizotypal and other personality disorder traits," the team writes in TheAmerican Journal of Psychiatry.
For the study, all patients and first-degree relatives, plus 295 mentally healthy controls, completed the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychologic battery. Overall, cognitive impairment worsened with the severity of psychosis, with average z scores ranging from -1.42 for the 293 schizophrenia patients to -0.77 for the 227 psychotic bipolar disorder patients.
Patients with schizoaffective disorder had intermediate z scores, which were slightly worse in the 55 patients who were depressed than the 110 who were manic. Overall, BACS scores worsened as affective symptoms decreased and psychotic symptoms increased.
"These findings parallel those of previous reports of more severe cognitive impairments in schizophrenia than in psychotic affective disorders and support dimensional rather than robust categorical models of psychotic disorders," note Hill et al.
However, another study recently reported by medwireNews showed that cognitive decline over time may be greatest among patients with schizoaffective disorder.
In the current study, cognitive impairment on the BACS was also present in 316 first-degree relatives of the schizophrenia patients, but not in 259 relatives of the psychotic bipolar disorder patients. On closer analysis, relatives who had elevated axis II traits had significantly impaired cognition regardless of whether they were related to schizophrenia or psychotic bipolar disorder patients, and whether they had cluster A (odd or eccentric) or cluster B (dramatic, emotional, or erratic) traits.
But among relatives without axis II traits, significant cognitive impairment was present in those who were related to schizophrenia patients but not in those who were related to psychotic bipolar disorder patients.
Based on this, the team suggests that "a potentially promising phenotyping strategy for tracking risk mechanisms in bipolar disorder might lie in evaluating the co-occurrence of personality traits and cognitive dysfunction."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter