Cognitive impairment in mental illness associated with faster cellular ageing

Cognitive impairment is associated with shorter telomere in people
with bipolar-schizophrenia spectrum disorders: Study

by Anne Crawford

Telomeres, the protective cap-like structures that stop the ends of our chromosomes from becoming frayed or tangled, are of increasing interest globally as markers of cellular ageing. Now a study led by Monash University Alfred Psychiatry research centre (MAPrc) researchers has revealed a link between telomere length and cognitive impairment in people with bipolar-schizophrenia spectrum disorders.

The collaborative study, guided by MAPrc’s Associate Professor Caroline Gurvich, found that cognitive impairment was associated with shorter telomeres in these people. The findings of the study, which spanned a decade, appeared in ‘Psychological Medicine’ this month.

Associate Professor Gurvich said that MAPrc studies and research elsewhere had previously established that there are subgroups of people with schizophrenia or bipolar disorder who have cognitive deficits compared to subgroups that don’t.

“Cognitive impairment has largely been ignored for years and it really is a key symptom,” she said. “The ability to think clearly, to have good memory or to be able to make decisions plays such a crucial role in daily lives, in being able to work or study and have meaningful relationships.

“Most medications don’t target cognition, so people are left with cognitive impairments even when, for example with schizophrenia, their hallucinations and delusions get better with their anti-psychotic medication. We need to better understand what’s underpinning these cognitive impairments so we can develop better treatments.

“We were trying to tease apart why some people have lots of difficulties with their thinking skills and others didn’t,” she said.

Associate Professor Gurvich said the study was aimed at investigating biological underpinnings of cognitive problems in people with schizophrenia, bipolar or schizoaffective disorder. “One theory that’s been put forward is that people with mental illness have accelerated biological ageing so their cognition becomes impaired at a much earlier age,” she said.

“Each time a cell divides, its telomeres become a little bit shorter and eventually they become so short that the cell stops dividing then the cell dies – so that’s why it’s a marker of cellular ageing. But for some people that process is accelerated and we don’t know exactly why. Genetic factors, biological factors and social factors all seem to play a role.”

The researchers, which included former PhD students, conducted cognitive tests and analysed blood samples in 73 people divided into cognitive subgroups in bipolar-schizophrenia spectrum disorders – a cognitively impaired subgroup and a relatively intact cognitive group. The samples tested telomere length, which were then compared against a healthy control sample of 113 people.

The data-driven cognitive subgroups did not differ in terms of duration or severity of their mental illness.
 
The researchers found that telomere length was significantly shorter in the severely impaired cognitive subgroup compared to the healthy control group, whereas the telomeres of the relatively intact group weren’t significantly shorter.

“It is one of the first studies to really show that cognitive impairment in mental illness is associated with shorter telomere length,” Associate Professor Gurvich said. “But we don’t know in terms of cause and effect if shorter telomeres are the cause of cognitive impairment or whether a similar underlying factor might lead to both cognitive impairment and shorter telomeres,” she said.

Associate Professor Gurvich, a clinical neuropsychologist, was first author on the paper. Collaborator, Professor Marco Romano-Silva (Department Saude Mental, Faculdade de Medicina, UFMG, Belo Horizonte, Brazil) introduced the concept of exploring telomere length; Dr Kiymet Bozaoglu, then at the Baker Institute, analysed telomere length; Dr Abdul-Rahman Hudaib, Monash Department of Psychiatry was the statistician; while Professor Susan Rossell (Swinburne) headed the CAGEMIS bio-data bank, which provided the samples.
 
Reference

Gurvich C, Thomas  N, Hudaib  A, Van Rheenen  TE, Thomas  EHX, Tan  EJ, Neill  E, Carruthers  SP, Sumner PJ, Romano-Silva M, Bozaoglu K, Kulkarni  J, Rossell SL. The relationship between cognitive clusters and telomere length in bipolar-schizophrenia spectrum disorders. Psychol Med. 2022 Aug 3;1-8.  doi: 10.1017/S0033291722002148.

More about Associate Professor Caroline Gurvich's research

HER Centre Australia research