You might have seen these papers already

A Prospective Follow-up of Patients With Bipolar and Primary Unipolar Affective DisorderGeorge Winokur, MD; William Coryell, MD; Martin Keller, MD; Jean Endicott, PhD; Hagop Akiskal, MD

Bipolar Disorders in a Community Sample of Older Adolescents: Prevalence, Phenomenology, Comorbidity, and Course

PETER M. LEWINSOHN et al

The course of illness is so variable between the patients that it is hard to answer your question.

Consider iatrogenic etiologies secondary to either dopamine antagonists or SSRIs.

Monsieur Bianchi summarises the situation perfectly.

regarding BPD best ways is make out side work or sports so that refresh your mind and body .

Hoping this article may either answer a few questions of endurance or lead to other sources.

I agree with dr. Bianchi answer which seems to me the more complete you can get for answering a not univoical question. Consider the comorbid clinical situation too in order to get more orientation in the complex area of patients with BPD and attachment pattern. Concerning the latter point you can also consider our paper Barone L., Fossati A., Guiducci V. Attachment mental states and inferred pathways of

development in Borderline Personality Disorder: A study using the Adult Attachment Interview, Attachment and Human Development, 13 (5), 451-469

Anhedonia is a core symptom of depression. It`s one of the two main criteria for Major Depressive Episode in DSM. If it persistis I`d consider the patient is presenting a partial remission and the patient is still suffering a depression, and so more treatment is needed.

While taking the antidepressant? Can be a side effect of this. It disappears when the drug is stopped and not just be a symptom of depression

If you would like to measure Anhedonia you might want to check out the Hospital Anxiety and Depression Scales. The Depression scale measures Anhedonia. 

please make out side exercise and  wake up early morning every day,

this is one of the cure your symptom.