As both groups did not differ significantly in telomere length, depression-associated TL shortening did not significantly recover since the last depressive episode in comparison to the controls – assuming no differences in pre-depression TL.
Our results support the findings of Verhoeven and colleagues [ 28] who also investigated telomere length in depression and found no differences between current and remitted depressed individuals.
In addition to investigating telomere length in depression, we were interested in assessing biological factors associated with telomere shortening.
In the case of the posttetanic contractions reported here, the enhancement apparently predominated at a short length, while depression was evident at long sarcomere length.
The regression incorporated age, sex, completion of university education, household income category, body mass index (BMI) category, cigarette smoking, alcohol use, exercise, length of depression diagnosis, type of diagnosing physician, and Charlson comorbidity index (CCI) as predictors.
It is possible that the perspectives of men and women, and people of differing ages, educational, social and cultural backgrounds, severity and length of depression demonstrate differing patterns of response.
It is interesting that the twitch contraction after a brief tetanic contraction at 22°C in our experiments demonstrated potentiation when the response was measured at short sarcomere lengths, and depression when the response was measured at long sarcomere lengths.
At longer sarcomere lengths, posttetanic depression was apparent, as the posttetanic twitch was smaller than the pretetanic twitch (Pt*/Pt < 1).
We also examined the impact of antidepressant treatment on the relationship between lifetime duration of depression and telomere length.
While shortened telomere length in chronic depression is consistent with findings in other chronically stressed and depressed populations [55], [58], [59], [61], [102], this measure is not specific to chronic stress or depression and thus is not useful as a specific diagnostic "biomarker".
