PARIS – Cumulative lifetime exposure to benzodiazepines and antidepressants in the relatively modest amounts typically prescribed in schizophrenia did not appear to adversely affect patients’ cognition in midlife, according to a first-of-its-kind study from Finland.

“These findings are reassuring,” said Anja P. Hulkko, MD, a psychiatric resident at the University of Oulu (Finland).

“The finding regarding antidepressants is especially important, because in the long-term treatment of schizophrenia, it’s often the case that patients develop depressive symptoms, and they are often underevaluated and undertreated. Our results show you can feel safe in treating them with antidepressant drugs,” she said in an interview.

“Similarly, you don’t need to worry about using benzodiazepines in schizophrenia if you are using small doses or for short periods to treat a specific condition like anxiety or sleeplessness,” Dr. Hulkko said at the annual congress of the European College of Neuropsychopharmacology.

These observations were among the key findings of her analysis from the Northern Finnish Birth Cohort 1966. This ongoing unique and naturalistic observational study – or actually, more than 20 different studies conducted in the same population – was designed to study risk factors involved in preterm birth and intrauterine growth retardation, as well as the consequences of these early adverse events on later morbidity and mortality. Data including maternal health during pregnancy have been prospectively collected from first prenatal contact at weeks 10-16 well into adulthood.

The 1966 cohort included 12,058 live births in the two northernmost provinces of Finland, which was 96% of all births there in that year. DNA samples were obtained from nearly 6,000 subjects in the cohort. After birth and again every 7-15 years, the offspring were examined and underwent clinical evaluation in which a wide range of phenotypic, behavioral, and demographic data were collected. Linkage to Finland’s comprehensive national registries provides investigators with up-to-date information about participants’ education, medication, hospitalizations, significant medical diagnoses, pensions, and death. These prospective data allow investigations of the importance of genetic, biologic, social, and behavioral risk factors in the emergence of various target diseases, one of which is schizophrenia.

Dr. Hulkko’s presentation focused on 60 patients with various schizophrenia spectrum disorders who underwent an extensive battery of neuropsychological tests at age 43, when they averaged 16.5 years of illness.

Lifetime cumulative exposure to benzodiazepines or antidepressants was not significantly associated with a global composite cognition score in a multivariate analysis adjusted for potential confounders including sex, age at schizophrenia onset, and lifetime psychiatric hospital treatment days.

The comprehensive test battery included the California Verbal Learning Test, the Abstraction Inhibition and Working Memory Task, Digit Span and Matrix Reasoning, verbal fluency and vocabulary testing, and the Visual Object Learning Test.

This, she said, is the first report to look at the cognitive impact of these drug classes in midlife schizophrenia. Long-term, high-dose use of benzodiazepines has in recent years been linked to increased risk for cognitive impairment in other populations, but that’s not ordinarily how those drugs are employed in schizophrenia.

In contrast to the new Finnish antidepressant and benzodiazepine findings, higher lifetime antipsychotic dose-years in the study population were recently reported by Dr. Hulkko’s senior coinvestigators to be significantly associated with a worse adjusted cognition score, with no difference between typical and atypical antipsychotics. “It is possible that large antipsychotic doses harm cognition in schizophrenia in the long term,” the researchers concluded (Psychiatry Res. 2017 Jan;247:130-8).

At the meeting, Dr. Hulkko presented new data on the cognitive impact of cumulative exposure to antipsychotics in the midlife schizophrenia cohort. The new finding is that having an antipsychotic-free period of at least 1 year at any point since treatment started an average of more than 16 years earlier was associated with a better adjusted cognitive performance.

The same was true for having an antipsychotic-free interval of at least 11 months directly before administration of the neuropsychological test battery. This is an encouraging finding because it suggests that an antipsychotic drug holiday might promote a measurable degree of cognitive recovery. But this observation must be viewed as hypothesis generating rather than conclusive, given the relatively small size of the study population, the observational nature of the study, and the possibility that the patients on a pretest antipsychotic break had less severe illness.

“Although we have tried to control for many factors, still, it’s possible that we cannot control for everything,” she noted. “It seems likely that both the illness itself and treatment are associated with the course of cognition.”

Kamilla W. Miskowiak, PhD, a neuropsychologist at the University of Copenhagen deemed the Finnish results “highly interesting.”

“This is reassuring, since many patients are worried about taking these medications [antidepressants and benzodiazepines] because of their potential negative effects on cognition. In contrast, long-term high-dose antipsychotic medication was associated with poorer cognitive outcome. This underscores the importance of close dose monitoring of antipsychotic medication for these patients to improve their cognitive outcome,” said Dr. Miskowiak, who was not involved in the study.

The study was supported by the Academy of Finland, the Finnish Cultural Foundation Lapland Regional Fund, and grants from various nonprofit foundations. Dr. Hulkko reported having no financial conflicts of interest.

bjancin@frontlinemedcom.com

Benzodiazepines and antidepressants do not impair cognition in midlife schizophrenia