1,6 million French people have bipolar disorder. This serious pathology is characterized in particular by alternating depressive episodes and phases of excitement. Between these cycles, the patient’s mood tends to normal, it is euthymia.

Everyone has their ups and downs. It is normal to take turns feeling joy, sadness, and anger. However, bipolar disorder (formerly called manic-depressive disorder) is a medical condition. People who have it experience extreme mood swings called “manias” that are unrelated to what is happening to them and affect the way they think and act, affecting every aspect of their life.

These symptoms can also include episodes of depression.

Individuals with bipolar disorder often have a more developed, expressed affectivity than the general population. They can feel excited, impulsive, euphoric, and full of energy. During manic episodes, they can also engage in extreme behaviors such as unprotected sex or drug use. Bipolar disorder is not a rare brain disorder. Bipolarity is often familial like depression. In fact, bipolar disorders are more frequently found in people where at least one of the parents is himself suffering from bipolar disorder or depression. The former are increasingly detected during adolescence and early adulthood. People with bipolar disorder frequently have other mental disorders such as anxiety disorders, substance use disorders and / or attention deficit / hyperactivity disorder (ADHD). The risk of suicide is significantly higher in people with bipolar disorder than in the general population. According to the WHO, bipolar disorder is one of the 10 most disabling and costly diseases in the world.

Bipolar disorder is generally characterized by 3 conditions:

• a state of euphoria or restlessness called “mania”;
• a state of depression, called “depression”;
• a condition without symptoms or “euthymia”. This term describes a relatively stable state of mood, in which symptoms are minimal, in which the person is not manic, hypomanic or depressed. But, this inter-critical period, is it a period free of symptoms or a period parasitized by residual symptoms and what is the driving force of this period at the symptomatic level?

People with bipolar disorder experience intense emotional states that usually occur over distinct periods of several days to several weeks. This notion was introduced by Jean-Pierre Falret, a XNUMXth century researcher and alienist doctor whose discoveries and his humanism paved the way for modern psychiatry. He coined the term “circular madness to designate these periods of excitement and melancholy. At the same time, Jules Baillarger defined “double form madness” by phases of partial remission between attacks. The latter thus suspected the persistence of a residual symptomatology between the episodes. Then, this period called “euthymic” or “intercritical” has long been neglected, the majority of studies focusing on the episodes themselves.

For twenty years now, bipolar disorders have been well known and benefit from better visibility. More recently, over the last 5 to 10 years, studies have shown the presence of residual symptoms (persistent symptoms linked to bipolar disorder during the inter-episodic phase and which will have an impact on functioning) associated with these periods of apparent stability that are the inter-critical periods. They will have an impact on the psychosocial functioning of the individual, and can also be associated with an increased risk of relapses. These residual symptoms involve four clinical dimensions during the inter-episodic period:

• the emotional dimension;
• the thymic dimension (marked mainly by residual depressive symptoms);
• cognitive impairment;
• sleep disorders and circadian rhythms.

The inter-episodic period or euthymia phase considered to be associated with clinical stabilization of the disorder.

According to Dr. Masson, beyond appearances, a bipolar patient who is not in crisis, does not necessarily feel well. According to the doctor, this period between two seizures, which he calls the “interictal period” requires the same regular monitoring as during the depressive and arousal phases. It is estimated that 50% of patients with bipolar disease have this type of residual symptoms apart from seizures. The manifestations are insufficient to be considered as relapses. It is therefore important to follow them in order to prevent recurrences and the possible risk of suicide. In addition to these symptoms, certain cognitive disorders such as difficulty concentrating or memory loss may be observed. Added to this, the bipolar often suffers from emotional hyperresponsiveness, which therefore significantly affects their quality of life. So much reason to ensure, even in periods of euthymia, a regular and attentive follow-up of these patients.