Serum levels of glial cell line-derived neurotrophic factor as a biomarker for mood disorders and lithium response

A systematic review of the biomarkers associated with cognition and mood state in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a severe psychiatric disorder characterized by changes in mood that alternate between (hypo) mania or depression and mixed states, often associated with functional impairment and cognitive dysfunction. But little is known about biomarkers that contribute to the development and sustainment of cognitive deficits. The aim of this study was to review the association between neurocognition and biomarkers across different mood states.

METHOD

Search databases were Web of Science, Scopus and PubMed. A systematic review was carried out following the PRISMA guidelines. Risk of bias was assessed with the Newcastle-Ottawa Scale. Studies were selected that focused on the correlation between neuroimaging, physiological, genetic or peripheral biomarkers and cognition in at least two phases of BD: depression, (hypo)mania, euthymia or mixed. PROSPERO Registration No.: CRD42023410782.

RESULTS

A total of 1824 references were screened, identifying 1023 published articles, of which 336 were considered eligible. Only 16 provided information on the association between biomarkers and cognition in the different affective states of BD. The included studies found: (i) Differences in levels of total cholesterol and C reactive protein depending on mood state; (ii) There is no association found between cognition and peripheral biomarkers; (iii) Neuroimaging biomarkers highlighted hypoactivation of frontal areas as distinctive of acute state of BD; (iv) A deactivation failure has been reported in the ventromedial prefrontal cortex (vmPFC), potentially serving as a trait marker of BD.

CONCLUSION

Only a few recent articles have investigated biomarker-cognition associations in BD mood phases. Our findings underline that there appear to be central regions involved in BD that are observed in all mood states. However, there appear to be underlying mechanisms of cognitive dysfunction that may vary across different mood states in BD. This review highlights the importance of standardizing the data and the assessment of cognition, as well as the need for biomarkers to help prevent acute symptomatic phases of the disease, and the associated functional and cognitive impairment.

Major depressive disorder: biomarkers and biosensors

Depressive disorders belong to highly heterogeneous psychiatric diseases. Loss of in interest in previously enjoyed activities and a depressed mood are the main characteristics of major depressive disorder (MDD). Moreover, due to significant heterogeneity in clinical presentation and lack of applicable biomarkers, diagnosis and treatment remains challenging. Identification of relevant biomarkers would allow for improved disease classification and more personalized treatment strategies. Herein, we review the current state of these biomarkers and then discuss diagnostic techniques of aimed to specifically target these analytes using state of the art biosensor technology.

Gender differences in plasma glial cell line-derived neurotrophic factor levels of patients with bipolar disorder

BACKGROUND

The glial cell line-derived neurotrophic factor (GDNF) has an important role in neurons and is closely associated with psychiatric disorders. The development of bipolar disorder (BD) may differ between genders. Existing studies have shown that plasma GDNF levels are altered in patients with BD. In this study, we investigate whether the GDNF levels in patients with BD differ in terms of gender.

METHODS

Participants were divided into the BD group (n = 76, with 26 males and 50 females) and healthy control (HC) group (n = 89, with 35 males and 54 females). Plasma GDNF levels were detected via multifactor assay. Clinical symptoms of patients with BD were collected and assessed using the Hamilton Depression-17 Inventory, Hamilton Anxiety-17 Inventory, Young's Mania Rating Scale, and Brief Psychiatric Rating Scale.

RESULTS

The GDNF levels were significantly higher in all participants in the HC group (F = 4.262, p < 0.05) compared with those in the BD group. In the HC group, the males (t = 4.814, p < 0.001) presented significantly higher levels than the females. The plasma GDNF levels in males in the BD group (t = 3.022, p < 0.05) were significantly lower than those in males in the HC group.

CONCLUSION

Differences in plasma GDNF levels are associated with the gender of patients with BD.

Glial cell line-derived neurotrophic factor (GDNF) in blood serum and lacrimal fluid of patients with a current depressive episode

BACKGROUND

Many studies indicate a significant role of GDNF in the pathogenesis of the mood disorders, including bipolar disorder (BD) and major depressive disorder (MDD). Potentially, neurotrophic factors in lacrimal fluid (LF) could become biomarkers of various specific disorders. The aim of this study was to assess GDNF levels in LF and blood serum (BS) of patients with a current depressive episode (cDE).

METHODS

We studied the glial cell line-derived neurotrophic factor (GDNF) concentration in the LF and BS of 39 healthy controls and 137 patients with a current depressive episode (cDE) (both subgroups members were 20-49 years): BD - 46 patients, MDD - 91 patients.

RESULTS

GDNF concentration in BS of women with MDD was significantly lower than in men. In BD patients, univariate linear regression analysis revealed significant correlations between GDNF concentration in the LF and the use of anxiolytics or antidepressants. These correlations were confirmed by the multivariate linear regression analysis. A significant correlation between GDNF concentrations in the LF and BS was found in controls.

LIMITATIONS

The unequal proportion of men in the BD group did not permit adjusting GDNF concentrations for sex. The collected LF was stimulated, which could influence GDNF levels. It should also be noted that the patients included in the study were not treatment- naïve.

CONCLUSIONS

Our findings suggest that GDNF concentration in LF could be a biomarker of the cDE (both unipolar and bipolar), though the sensitivity of this potential biomarker may be lower in depressive patients with anxiety symptoms.