Psychiatric Complications of Bariatric Surgery

Etiology

Psychiatric complications from bariatric surgery can be attributed to various factors.

Preexisting Psychiatric Conditions and Their Impact on Bariatric Surgery Candidates

The most likely risk factor for developing psychiatric complications following bariatric surgery is the presence of one or more psychiatric disorders before the operation.[9] Common psychiatric conditions observed in bariatric surgery candidates include depression, anxiety, substance use disorders, and binge-eating disorder.[10] Untreated eating disorders (most concerning being anorexia nervosa or bulimia nervosa), psychotic symptoms, severe depression, or active substance use disorders are considered relative contraindications for bariatric surgery.[11] However, it is important to note that these preexisting psychiatric conditions are not absolute contraindications, and individualized treatment or active substance use disorders are considered relative contraindications for bariatric surgery.

Bariatric surgery constitutes a significant, life-altering event that has the potential to spur mental illness de novo. The likely explanations include drastic dietary changes in the postoperative period, including consuming smaller portions and adjusting to new food types. Behavioral restrictions, such as eating slowly or only during certain times (while avoiding late-night eating), also contribute to this transition. In addition, complications such as dumping syndrome may induce anxiety, while excess skin resulting from significant weight loss has the potential to alter body image perception, potentially leading to distress.

Preoperative psychiatric comorbidities have the potential to significantly influence outcomes post-bariatric surgery. Research indicates that patients with depression who undergo bariatric procedures tend to experience less weight loss compared to those without depression.[12][13] Similarly, a history of binge-eating disorder can also affect weight loss outcomes post-surgery.[14] Moreover, individuals with alcohol use disorder exhibit higher rates of alcohol consumption beyond the initial 2-year postoperative period, as evidenced by findings from a meta-analysis.[15]

Nutritional Deficiencies and Their Psychological Effects

Various micronutrient deficiencies following bariatric surgery have been reported due to food absorption changes. Commonly reported deficiencies include vitamins D and B12, thiamine, folate, iron, and zinc.[16] Research has demonstrated a strong link between vitamin D deficiency and depression.[17] Wernicke encephalopathy in the setting of chronic emesis and resulting thiamine deficiency has been associated with psychotic symptoms in the postoperative period.[18] Vitamin B12 deficiency can contribute to psychotic symptoms in the postoperative period; however, along with thiamine deficiency, these symptoms would likely also be accompanied by neurological changes.[19] 

Restrictive procedures such as sleeve gastrectomy, adjustable gastric banding, and vertical gastric banding generally result in fewer micronutrient deficiencies compared to malabsorptive or combined-type procedures, such as RYGB and BPD.[20] A recent review assessed the risk of micronutrient deficiencies between restrictive and malabsorptive or combined procedures. Although all types of procedures were associated with deficiencies, malabsorptive or combined types increased the risk of vitamin B12 deficiency by over 3-fold compared to restrictive procedures, owing to reduced parietal cells and decreased production of intrinsic factors.[19] In addition, mineral deficiencies such as iron and calcium are more prevalent with combined-type procedures, as the main sites of absorption for these minerals occur in the duodenum and proximal jejunum, which are bypassed with this procedure. As a result, a study revealed that anemia occurred in nearly half of all patients undergoing RYGB, affecting approximately 17% of those undergoing restrictive-type procedures.[21]

The effect of vitamin D absorption varies depending on the type of surgery undergone. According to a recent review, sleeve gastrectomy showed no deficiencies in vitamin D absorption at multiple postoperative time points (3, 6, and 12 months). Additionally, compared to preoperative states, the risk of vitamin D deficiency decreased following sleeve gastrectomy. However, deficiencies in vitamin D were observed in up to 10% of patients at the 12-month postoperative mark.[22]

Gut-Brain Axis

Alterations in the gut microbiome can impact mood and behavior by influencing gut peptides such as ghrelin, glucagon-like peptide 1, peptide YY, and cholecystokinin. These gut peptides have also been associated with increased rewarding effects of alcohol post-bariatric surgery.[23] Interestingly, the emergence of glucagon-like peptide 1 agonists in obesity treatment has led to modulations of reward pathways, offering potential avenues for addiction treatment, as suggested by Brown et al.[23] Furthermore, alcohol and other substance use have also been linked to gut dysbiosis, potentially creating a vicious cycle affecting mood and behavior.

Behavioral Changes and Addiction Transfer

Postoperative addiction transfer emerges as a significant psychiatric complication of bariatric surgery. Patients who previously relied on eating as a maladaptive coping mechanism for underlying mental illness and distress may face challenges when this option is limited post-surgery due to physical changes reducing stomach capacity. Consequently, they may replace their prior addictive eating habits with new or exacerbated substance use.[24] Substance use in the postoperative period is prevalent, with alcohol being the most commonly reported substance used.[25] There have been numerous reports of bariatric surgery patients ultimately dying from cirrhosis during the postoperative period.[26] Particularly alarming among these changes is the heightened risk of suicide in the postoperative period, a phenomenon consistently observed across multiple studies.[27] This phenomenon likely arises from a combination of factors, including postoperative dietary and behavioral constraints, along with dissatisfaction regarding weight loss or harboring unrealistic expectations that bariatric surgery will resolve many of the patients' preexisting struggles.

Epidemiology

Individuals eligible for bariatric surgery, as well as those who undergo the procedure, often experience depression, anxiety, and specific eating disorders, such as binge eating, with prevalence rates exceeding 15%.[5] Although the occurrence of other mental health conditions like psychoses is relatively rare, reported prevalence rates, particularly for depression and binge eating disorder, exhibit considerable variation. Studies conducted within veteran populations indicate a higher prevalence of comorbid conditions, particularly posttraumatic stress disorder, compared to other groups.[28]

Studies conducted within veteran populations have indicated that rates of depression, anxiety, and eating disorders decrease at various reference points following bariatric surgery.[28] However, other studies have shown that a significant proportion of patients develop "loss of control" eating habits within 2 years post-surgery. This term is defined as difficulty controlling eating behaviors despite not meeting the formal criteria for a binge-eating disorder.[29] 

Bariatric surgery has also been found to be associated with an increased risk for self-harm and suicide, as well as alcohol use disorders in the postoperative period. In a recent study, the relative risk for suicide was found to be 64% higher in the surgical cohort compared to the nonsurgical cohort.[30] Additional studies have supported these findings, indicating increased alcohol use following bariatric surgery. One recent study reported alcohol use rates ranging from approximately 7.6% to 11.8% among patients who underwent bariatric surgery.[31]

Pathophysiology

The pathophysiology of psychiatric complications following bariatric surgery appears to involve a complex interplay of physiological, psychological, and nutritional factors.[23] Surgically induced modifications to the gastrointestinal tract can potentially disrupt the gut microbiome and alter normal absorption processes, which may affect the pharmacokinetics of alcohol, other substances, and various medications.[23] Such changes could conceivably lead to higher plasma concentrations of these substances, potentially amplifying their psychological effects and contributing to the onset or worsening of psychiatric symptoms.

Nutritional deficiencies that often follow bariatric surgery, such as deficits in vitamins D and B12, iron, and thiamine, may significantly contribute to the development of psychiatric issues.[9] These deficiencies can lead to neurological symptoms that mimic or exacerbate mental health conditions.[12] Furthermore, alterations in the gut-brain axis, involving hormonal and neuronal communication pathways, may influence mental health outcomes.[23] Hypothetically, changes in gut-derived hormones, such as ghrelin and peptide YY, can impact mood regulation and behavior, possibly exacerbating conditions such as depression and anxiety. Moreover, altered absorption of nutrients and medications may also compromise the effectiveness of prescribed psychiatric drugs, potentially resulting in suboptimal control over preexisting mental health conditions.

Additionally, the presence of preexisting psychiatric disorders such as MDD or anxiety can significantly influence the likelihood and severity of postsurgical psychiatric complications. Psychological stressors associated with adjustments to postoperative lifestyle—such as notable changes in body image and restrictive eating patterns—may further complicate the psychiatric landscape. The inability to use food as a coping mechanism, often referred to as "emotional eating," may leave some patients with fewer strategies for managing stress, potentially leading to an increase in compulsive behaviors or substance use. These complex pathways highlight the necessity for comprehensive mental health assessments and strong nutritional support for patients undergoing bariatric surgery. Further research is essential to fully understand the intricate mechanisms underlying the psychiatric complications observed after bariatric surgery.

History and Physical

Presurgical Assessment for Bariatric Surgery Candidates

Candidates for bariatric surgery must undergo a comprehensive psychiatric evaluation, which helps establish a baseline psychiatric profile and facilitates ongoing monitoring of any postsurgical psychiatric symptom changes. The assessment should be structured as mentioned below.

History of present illness: This section should highlight any psychiatric symptoms that might have influenced the patient's decision to pursue bariatric surgery, including eating disorders contributing to significant weight gain.

Social history: A patient's preassessment social history should include detailed information relevant to the patient's current life situation and capacity to adhere to surgical aftercare, which significantly influences postoperative success. Key areas to explore include:

• Occupational status and available support systems
• Level of education
• Substance use history, detailing type, amount, frequency, duration, last use, cessation attempts, and methods of administration
• Access to firearms

Past psychiatric history: Documentation should include all pertinent past psychiatric details as follows:

• Diagnoses and hospitalizations
• Medication trials
• Incidents of self-harm or suicide attempts
• Previous therapeutic interventions

Past medical and surgical history: Information of any relevant medical and surgical history should be recorded, including:

• Diagnoses and hospitalizations
• Current medications
• Previous surgeries and their outcomes

Family psychiatric history: This section should include any psychiatric diagnoses within the family, along with any relevant medication histories or genetic predispositions to psychiatric conditions.

Mental status examination: A detailed examination should be performed to assess the patient's current psychiatric condition. This should include the following evaluations:

• Appearance (eg, grooming and attire)
• Sensorium and orientation
• Mood and affect (noting any discrepancies)
• Thought processes and content (assessing logical thinking and the presence of delusions or harmful ideations)
• Perceptions (checking for any hallucinations)
• Insight and judgment (essential for evaluating capacity to consent)
• Speech and motor activity
• Cognitive functions, such as attention and abstraction (using simple tests such as interpreting idioms)

Postsurgical Assessment for Bariatric Surgery Patients

During follow-up, both medical and psychiatric symptoms must be thoroughly evaluated. The clinician's assessment should proceed as follows:

• Signs of MDD or other mood disorders should be identified as outlined in the DSM-5. Symptoms such as anhedonia, dysphoria, fatigue, appetite changes, guilt, and psychomotor alterations must be consistently present for a minimum of 2 weeks.
• Eating disorder behaviors (eg, binge eating, purging, and undue dietary restrictions) should be carefully monitored.
• Weight changes should be tracked over time to verify healthy progress.
• The mental state of the patient should be evaluated for any new or worsening symptoms such as delusions, hallucinations, or paranoia.
• Substance use should be reviewed carefully, particularly for signs of alcohol use disorder, which is a common complication after bariatric surgery.

This structured approach to pre- and postsurgical assessments ensures a holistic evaluation of the patient's readiness and ongoing response to bariatric surgery, identifying any psychiatric barriers to successful outcomes.

Evaluation

Given the elevated suicide risk among postoperative bariatric surgery patients, it is prudent to implement a systematic screening program for depression and suicidal ideation. Such a program can be effectively integrated into routine follow-up consultations. The Patient Health Questionnaire (PHQ-9) is a recommended tool for this purpose. This brief self-administered survey comprises 9 items, each scored from 0 to 3, resulting in a potential total score ranging from 0 to 27. The PHQ-9 effectively targets vital symptoms of depression, such as anhedonia, dysphoria, fatigue, appetite irregularities, feelings of guilt, lack of motivation, difficulty concentrating, changes in motor activity (such as agitation and retardation), and thoughts of suicide, by assigning scores based on the frequency of these symptoms over the assessment period.[32] 

 A score greater than 10 on the assessment indicates at least moderate depression, warranting consideration for counseling and pharmacotherapy. A score exceeding 15 indicates the necessity for active pharmacotherapy and psychotherapy treatment. Finally, a score surpassing 20 indicates an immediate need for pharmacotherapy and an expedited referral to a psychiatrist, psychologist, or therapist for collaborative treatment. Furthermore, any positive response to question 9, which specifically inquires about suicidal thoughts, should prompt an immediate risk assessment for the threat of imminent danger to the patient.

Other psychometric tools, including the Columbia Suicide Scale, can be used to assess suicide risks further. If necessary, immediate consultation with a psychiatrist should be obtained and acute hospitalization pursued. Alongside screening for depression, it is imperative to thoroughly investigate the patient's eating habits, with particular attention to potential eating disordered behaviors, and closely monitor their weight trends.

The patient should also be screened for potential substance use after surgery. One useful psychometric tool for assessing substance use is the Screening, Brief Intervention, and Referral for Treatment (SBIRT) tool.[33] In patients presenting with anxiety symptoms, a thorough history and physical examination are necessary to exclude organic diseases, including dumping syndrome. Cardiac causes of palpitations should also be explored, considering the likelihood of electrolyte imbalances in the postoperative period.[34] An electrocardiogram (ECG), metabolic panel, and serum magnesium and phosphorus should be obtained to assess for possible abnormalities.

Treatment / Management

When initiating pharmacotherapy, the treating psychiatrist should specifically consider the patient's history of bariatric surgery. Bariatric procedures alter the absorption and metabolism of food, vitamins, minerals, and medications. Reduced gastric volume and increased gastric emptying affect drug absorption, favoring immediate-release over modified-release formulations.[35] Gastric pH increases due to reduced surface area and fewer parietal cells, potentially affecting pH-dependent drugs.[36] In addition, the volume of distribution of lipophilic medications is higher in obese patients, as the drug tends to accumulate in adipose tissue. Consequently, dosage adjustments may be necessary after weight loss.[36]

Cytochrome P450 3A enzymes subfamily constitute nearly 80% of the total P450 content in the small intestine.[37] Consequently, the gastrointestinal rearrangement after bariatric surgery, especially RYGB, significantly affects the oral bioavailability of CYP3A substrates. Medications metabolized by CYP3A4 may undergo faster metabolism, potentially leading to subtherapeutic levels. Some studies have demonstrated increased activity of CYP3A, CYP2B6, and CYP1A2 after bariatric surgery.[38] These changes could theoretically alter the plasma levels of medications metabolized by these enzymes. Other studies after RYGB have shown decreased levels in CYP2D6, CYP1A2, and CYP2C9, potentially affecting the metabolism of various psychiatric medications, including antidepressants and antipsychotics such as clozapine.[38] (A1)

Notably, studies do not consistently find changes in the CYP P450 level.[39] Studies following sleeve gastrectomy have found increased activity for CYP3A4 and decreased activity for CYP2C9 and CYP1A2.[38] Therefore, clinicians must remain vigilant for any relapse of psychiatric symptoms or the development of adverse effects with medications after bariatric surgery. Changes in cytochrome P450 activity may stem from reduced inflammation and hepatic lipid peroxidation due to weight loss resulting from bariatric surgery.[38]

Multiple studies have found a significantly lower area under the curve  (AUC) for selective serotonin reuptake inhibitors (SSRIs) following RYGB, which may prompt higher doses than those recommended by the US Food and Drug Administration (FDA) in these patients.[40][41]In addition, duloxetine, the selective norepinephrine reuptake inhibitor (SNRI), showed decreased absorption following RYGB, while venlafaxine showed no change in absorption.[36] The treatment of psychiatric complications after bariatric surgery will depend on the patient's specific psychiatric diagnosis. However, extra consideration must be given when prescribing certain medication groups.

Antipsychotics

Antipsychotic absorption may be altered following bariatric surgery. Specifically, both lurasidone and ziprasidone require dosing with food, and the respective levels for each drug may be changed in the setting of increased gastric pH. When prescribing antipsychotics, depot formulations may be considered, as they will not be affected by decreased absorption. A serum level of an antipsychotic may be requested, when available and appropriate, to guide treatment.

Mood Stabilizers

Valproic acid concentrations can be decreased following malabsorptive procedures secondary to reduced absorption.[42] Levels should be checked for efficacy and toxicity, with both total and free levels monitored.

Carbamazepine and oxcarbazepine levels can be reduced following malabsorptive or combined-type procedures.[43] Lamotrigine has been theorized to have increased, decreased, or potentially unchanged drug levels following malabsorptive or combined-type procedures.[44] Clinicians should be aware of these potential changes in drug levels that may alter both efficacy and toxicity and drug levels should be monitored accordingly.

Lithium concentrations can increase significantly following bariatric surgery. Several case reports have detailed lithium toxicity following bariatric surgery, as increases in gastric pH can increase levels of the deprotonated form of lithium.[45] In addition, dehydration is a common complication of bariatric surgery and can also result in potentially toxic levels of lithium. As a result, a baseline lithium level should be obtained before surgery when the patient is therapeutically controlled, and this level should be monitored frequently in the postoperative period to ensure both therapeutic efficacy and to guard against potential toxicity.(B3)

Malabsorptive procedures will also decrease the effectiveness of oral contraceptives. Therefore, when potentially prescribing teratogenic medications, such as valproic acid or lithium, clinicians should be aware of this potential interaction and encourage different forms of birth control, such as intrauterine devices, contraceptive injections, or barrier protection.[46]

Antidepressants

Limited data exist regarding psychopharmacological options for bariatric surgery patients. When treating depression, weight-neutral antidepressants should be preferred. Given the potential for electrolyte derangement, specific care should be taken when choosing an antidepressant. Due to the cardiac adverse effects and the predisposition to electrolyte imbalances post-bariatric surgery, tricyclic antidepressants should be avoided unless clinically warranted.[47] Similarly, given the dietary restrictions of monoamine oxidase inhibitors, they are likely not a preferred option in patients who have undergone bariatric surgery.[48] Within the SSRI class, sertraline is likely a preferred agent due to its relative lack of QTc prolongation and a lower propensity to cause weight gain.[49][50](B3)

Fluoxetine, fluvoxamine, and paroxetine exhibit increased CYP450 inhibition relative to other SSRIs, and this should be considered for potential drug-drug interactions.[51] Citalopram has demonstrated clinically significant QTc prolongation in numerous studies and likely should be avoided if possible.[52] Although escitalopram does not appear to prolong QTc to the same extent as citalopram, given that it is the S-enantiomer of racemic citalopram, special care should be taken if prescribed to postoperative bariatric surgery patients.[53](A1)

Atypical antidepressants such as bupropion and mirtazapine should be used with caution. Although in a study, bupropion was associated with more significant reductions in weight loss after bariatric surgery in patients with depression, it has a well-documented risk for seizures, particularly in patients with a history of electrolyte derangement.[54] Mirtazapine antagonizes histaminergic receptors, leading to weight gain.[55] 

Treatment for Alcohol Use Disorder

In cases where a patient presents with Wernicke encephalopathy, typically associated with poor micronutrient absorption or prolonged vomiting, immediate and aggressive parenteral thiamine replacement is crucial. The Royal College of Physicians advises administering 500 mg of intravenous thiamine 3 times daily for the first 3 to 4 days, followed by 250 mg 3 times daily for the next 2 to 3 days. After the initial parenteral treatment, indefinite oral thiamine supplementation should be continued.[56] Wernicke encephalopathy is a potentially devastating neuropsychiatric illness with downstream impairments that can be severe. With higher intravenous dosing, anaphylaxis is a rare event, and patients must be monitored for this.[57] Postoperative substance use is common in bariatric surgery patients, necessitating a comprehensive, interdisciplinary approach to their care.

Alcohol use disorder is the most common substance use reported in the postoperative period. Acamprosate, disulfiram, and naltrexone are FDA-approved to treat alcohol use disorder.[58] Topiramate has been used off-label to treat alcohol addiction with varied success.[59]

Twelve-step programs such as Alcoholics Anonymous are superior to other behavioral therapies, including cognitive behavioral therapy, and are proven to lead to more abstinence days.[60] In particular, cognitive behavioral and dialectal behavioral therapies have proven effective in treating numerous psychiatric disorders in bariatric surgery patients.[61][62] Additionally, acceptance and commitment therapy has shown positive results in bariatric surgery patients concerning eating-disordered behaviors, body image perception, and quality of life.[63](A1)

Differential Diagnosis

The differential diagnoses for psychiatric complications of bariatric surgery include:

Micronutrient Deficiencies

Postoperative depression-like symptoms can be linked to deficiencies in essential nutrients such as vitamin D and iron, particularly following malabsorptive or combination procedures. Addressing these deficiencies promptly is vital.

Thyroid Disorders

Changes in thyroid function c can manifest as symptoms resembling anxiety or depressive disorders. Significant weight loss and altered nutritional intake following surgery can affect thyroid hormone levels, potentially requiring adjustments in thyroid medication.

Wernicke Encephalopathy

This condition, resulting from a deficiency of vitamin B1, presents with confusion, coordination problems, and visual disturbances, which can sometimes be mistaken for psychotic disorders. Monitoring thiamine levels and providing supplementation, if necessary, is crucial.

Electrolyte Imbalances

Electrolyte disturbances can produce symptoms resembling anxiety disorders, such as palpitations and a sense of impending doom. Conducting a complete metabolic panel is essential to identify any imbalances.

Dumping Syndrome

Dumping syndrome may exhibit symptoms similar to panic attacks, including palpitations and dizziness. Notably, it should be considered in the differential diagnosis for patients exhibiting such symptoms after surgery.

Prognosis

Several studies have noted that depression tends to initially improve in the early postoperative period following bariatric surgery, only to resurge after 2 to 3 years.[9] Closely monitoring depression and parasuicidal behaviors during the postoperative phase is crucial, and appropriate referrals and treatment should be initiated. Given the overall increased risk of suicide in the postoperative period, it is imperative to continue treatment until the patient and their physician can make a shared decision regarding the discontinuation of medication and psychotherapy.

Eating disorders are common among bariatric surgery patients, and proper screenings should be undertaken at follow-up appointments. While many patients may not meet the stringent DSM-5 criteria for binge-eating disorder due to the limited physical capacity for eating post-surgery, they often exhibit behaviors such as eating when not hungry, consuming food beyond physical fullness, and experiencing guilt regarding food intake.

Alcohol use is prevalent among patients seeking bariatric surgery, and this pattern often persists into the postoperative period. Currently, there is insufficient data to determine whether patients will experience remission or relapse from alcohol use disorder after bariatric surgery. However, available data suggest a significant number of deaths from alcoholic cirrhosis post-bariatric surgery.[26]

Numerous studies have demonstrated an increased risk of suicide in the postoperative period. Screening for suicidal ideation and parasuicidal behaviors is critical to help mitigate this risk. Overall psychopathology, including depression, eating-disordered behaviors, and substance use, can negatively impact weight loss during the postoperative period.[64] However, the anticipated weight loss may not align with the actual outcome, potentially resulting in dissatisfaction and added stress.

Complications

Bariatric surgery, while often hailed as a life-changing solution for patients with severe obesity, can introduce a host of psychiatric complications, with suicide being a particularly critical concern that demands careful attention. Postoperative psychiatric issues can range from exacerbation of preexisting conditions such as depression and anxiety to the development of new disorders such as substance use or eating disorders. The drastic changes in body weight and physiology after surgery can trigger emotional distress, body image concerns, and identity shifts—all of which may contribute to psychiatric distress. Moreover, rapid weight loss can lead to fluctuations in mood and cognition, impacting mental well-being. Additionally, nutritional deficiencies following surgery can affect brain function, exacerbating psychiatric symptoms. Clinicians caring for these patients should be aware of these potential complications and conduct screening, provide treatment, and make referrals for further management.