Bipolar disorder is a mood disorder marked by significant shifts in mood, energy, and daily functioning. These shifts range from elevated mood (mania or hypomania) to profound depression. Lithium has served as a foundational medication for decades, stabilizing these mood fluctuations.
Understanding How Lithium Works
Lithium’s exact mechanism in the brain is not fully understood, but theories suggest it influences systems involved in mood regulation. It modulates neurotransmitter activity, affecting serotonin, dopamine, and norepinephrine pathways. It increases inhibitory neurotransmission while reducing excessive excitatory signals.
Lithium also affects intracellular signaling pathways, such as adenyl cyclase, phosphoinositide, and protein kinase C, which may dampen overactive excitatory neurotransmission. It inhibits enzymes like glycogen synthase kinase-3 (GSK-3), involved in cellular processes within the central nervous system. Lithium may also offer neuroprotective effects, reducing oxidative stress and increasing protective proteins like BDNF and Bcl-2, while decreasing cell death processes.
Key Benefits of Lithium in Bipolar Disorder
Lithium offers therapeutic benefits for bipolar disorder by stabilizing mood. It reduces the frequency and severity of both manic/hypomanic and depressive episodes. A systematic review indicated that long-term lithium treatment can reduce the risk of bipolar manic relapse by approximately 42%.
Beyond acute mood stabilization, lithium prevents mood episode recurrence, offering long-term maintenance. This sustained effect contributes to a more stable emotional state and improved functioning. Lithium also reduces the risk of suicide in individuals with bipolar disorder, a risk notably higher in this population. Studies have consistently shown a lower rate of suicide-related events during periods of lithium treatment.
Potential Side Effects and Essential Monitoring
Lithium treatment has potential side effects, from common initial effects to long-term concerns. Initially, individuals may experience increased thirst, frequent urination, hand tremor, and nausea. These initial side effects often diminish as the body adjusts to the medication.
Long-term lithium use requires careful attention to kidney and thyroid function. It is linked to an increased risk of hypothyroidism and, less commonly, hyperthyroidism. It can also impact kidney function, increasing the risk of chronic kidney disease (CKD) stage 3 or higher. One study showed patients on lithium were nearly twice as likely to experience reduced renal function and more than double the risk of hypothyroidism.
Due to its narrow therapeutic window, regular blood tests are essential to monitor lithium levels, typically between 0.6 mmol/L and 0.8 mmol/L for maintenance, ensuring they remain safe and effective. Monitoring also includes periodic assessments of kidney (e.g., creatinine) and thyroid (e.g., thyrotropin) function to detect adverse effects early. This routine monitoring allows healthcare providers to adjust the dose as needed, preventing toxicity and managing long-term complications.
Living with Lithium Treatment
Long-term lithium therapy requires consistent management and communication with healthcare providers. Medication adherence is important to maintain stable mood and prevent relapse. Consistent hydration and salt intake are also important, as significant changes can affect lithium levels. For instance, less salt can increase lithium levels, while more salt can decrease them, influencing kidney excretion.
Individuals should be aware of drug interactions that can alter lithium levels. NSAIDs, certain diuretics, and some blood pressure medications can increase lithium concentrations, increasing toxicity risk. Discuss all medications and supplements with a healthcare provider to avoid harmful interactions.
Regular follow-up appointments are necessary for ongoing monitoring of lithium levels and overall health. If considering pregnancy, consultation is advised, as lithium use during pregnancy carries risks for the unborn baby. Lithium is often a long-term treatment, and consistent management contributes to its effectiveness and patient well-being.