Whether one looks for mental illness among homosexuals or homosexual interests among the mentally ill, the evidence clearly associates homosexuality with mental illness, a find not accounted for in terms of stigma, prejudice, and victimization of homosexuals. Recall that homosexuals are much more likely than heterosexuals to manifest multiple mental disorders in lifetime. Judging by the profile of nonheterosexuals among adolescents, especially school dropouts, and the relative overrepresentation of nonheterosexuals among delinquents/criminals and mentally ill individuals, comparisons between nonheterosexual college students and heterosexual college students almost certainly underestimate the prevalence of abnormal traits among nonheterosexuals. This is important in that studies on nonheterosexuals that have used college student samples have likely portrayed nonheterosexuals in a better light.

Recall the association between homosexuality and borderline personality disorder (BPD). Recall that one manifestation of BPD is repeated suicide attempts. Compared to heterosexual men, homosexual men are more likely to attempt suicide but the same cannot be said of successful suicides. Although from a clinical standpoint, one either has BPD or not, some people fail to meet the full diagnostic criteria of BPD but are close and are not mentally normal, as is true of various abnormal mental conditions that do not meet full mental disorder diagnostic criteria.1 In this regard, it is noteworthy that BPD represents an extreme along a continuum.2, 3 Therefore, repeated suicide attempts among male homosexuals are almost certainly a manifestation of mental illness. Besides, personality disorders, especially BPD, and worsening Axis I disorders, especially depression and substance use, predict suicide attempts.4

Several aspects of brain-drug interaction suggest that elevated substance use among homosexuals reflects disturbed brain functioning:

Some data:

  • Data from 14 placebo-controlled drug cross-over studies show that left-handers manifest greater EEG responses (indicative of electrical activity of the brain) to a wide variety of psychoactive drugs compared to right-handers and the differences are not brain hemisphere-specific.5
  • Schizophrenics with more minor physical anomalies experience greater side-effects of anti-psychotic drugs.6
  • Individuals with elevated fluctuating asymmetry and minor physical anomalies experience greater verbal memory deficits following caffeine ingestion.7
  • In an investigation of alcoholics compared to normal controls, alcoholic adults did not have a greater number of minor physical anomalies than normal adults, but the distribution among alcoholics appeared to be bimodal (having two peaks), suggesting heterogeneity within this group.8 It is likely that a number of alcoholics have experienced a disruptive uterine environment . Many studies have revealed elevated left-handedness among alcoholics,9 although some have not, which likely results from inadequate sample size. One study even reported atypical asymmetrical usage of eyes, ears, and feet among alcoholics compared to normal controls and heroin users.10
  • 40-50% of schizophrenics abuse recreational drugs, and among them substance use disorders are associated with incarceration, homelessness, violence and suicide, but more interestingly, there is little evidence “that schizophrenic symptoms lead to substance use (self-medication), that substance use leads to schizophrenia, or that there is a genetic relationship between schizophrenia and substance use.”11
  • Inducing lesions in various parts of the brain in rats increases the liability toward rapid dependence on drugs such as cocaine and stimulants.12, 13
  • As a general rule, substance use disorders are elevated among mentally ill individuals, and notably so for prisoners, schizophrenics and individuals with antisocial personality disorder or bipolar disorder.14

Homosexuals manifest elevated paraphilias. Paraphilias result from developmental disturbances:

Some evidence:

  • Paraphiles manifest elevated Axis I and Axis II mental disorders.15, 16
  • Pedophilia17 and zoophilia18 are more likely to accompany mental retardation . In a comparison of mental patients with two control groups (medical in-patients and psychiatric staff), the prevalence of bestiality (both actual sexual contacts and sexual fantasy) was 55% in the psychiatrically ill group but much lower in the control groups (10% and 15%, respectively).19 Recall that homosexual behavior is elevated among both mentally ill individuals and zoophiles.
  • Homosexual and paraphilic behaviors are more common among individuals with outcomes resulting from developmental disturbances such as schizophrenia and ADHD.20, 21
  • Furthermore, pedophiles manifest elevated anomalies:
    • A less dense right frontal area of the brain.22
    • A higher incidence of left hemisphere (brain) impairment.23
    • Smaller left frontal and temporal areas (portions of the brain) and increased brain asymmetry.24
    • Elevated non-right-handedness.25, 26, 27
    • Low baseline plasma cortisol and prolactin (cortisol and prolactin are hormones); and increased body temperature and multiple serotonergic abnormalities (serotonin is, among other things, a neurotransmitter, i.e., a substance that allows adjacent neurons to communicate with each other).28
    • An overactive sympathoadrenal system (referring to the innervation of the adrenal gland by the sympathetic nervous system).29
    • A study associated pedophilia with 1) childhood head injuries before age 6 years that resulted in unconsciousness and 2) psychiatric morbidity among the mothers of pedophiles.30 These injuries were also associated with attentional problems and left-handedness and head injuries after age 13 years in pedophiles were associated with drug abuse and promiscuity.31 Therefore, it cannot be necessarily assumed that the injuries contributed to the pedophilia because it is likely that prenatal disruptive factors increased the likelihood of both pedophilia and proneness to injury. Left-handed individuals appear more likely to experience injuries, a find not readily explicable in terms of their living in a world numerically dominated by right-handed individuals.32, 33 Traumatic head injuries in childhood or adolescence are associated with an elevated likelihood of various mental disorders in adulthood, especially mental illness co-existing with criminality.34

The above finds are not based on probability samples of pedophiles or other paraphiles, but then it is very difficult to obtain a probability sample of paraphiles. On the other hand, since many independent investigations of paraphiles reveal a high incidence of comorbid disorders or anomalies among them, it would be remarkable if all the above finds turn out to be an artifact of nonrepresentative samples.

The tendency for multiple paraphilias to co-occur associates paraphilias with poor canalization of development. Not only do homosexuals manifest elevated paraphilias, but the majority of self-identified homosexuals behave in a heterosexual manner at some point of their lives and also display a high variability of sexual behavior, i.e., compared to heterosexuals, the incidence of disparate erotic targets in the same individual is elevated among homosexuals. In the past homosexuality was initially classified as a sociopathic personality disorder in the DSM because of the assumed defective conscience of homosexuals, but soon thereafter, it was classified as a paraphilia and remained a paraphilia till it was declassified as a mental disorder.

There is a strong association between hypersexual desire and paraphilias or non-paraphilic sexual compulsion disorders; besides, paraphilias and non-paraphilic sexual compulsion disorders (NPSCDs) often co-occur. Other than being relatively overrepresented among paraphiles, homosexuals are also relatively overrepresented among individuals with NPSCDs. The incidence of Axis I disorders such as mood disorders, anxiety disorders, and substance use disorders as well as Axis II disorders (personality disorders)is especially elevated among individuals with paraphilias or NPSCDs,35, 36, 37, 38, 39 as is also true of homosexuals. Axis I and Axis II disorders are also elevated among various disorders listed in Table 140 below such as bulimia nervosa,41 binge eating disorder,42 pathological gambling,43, 44 compulsive buying,45 and trichotillomania.46

Table 1: Similarity Between OCD* and Some Disorders (published, 1994)
Disorder Phenomenology Male/Female Sex Course Occurs with OCD Comorbid mood disorders Family history Physiology Treatment response
Body dysmorphic disorder 3 3 3 3 3 2 - 3
Hypochondriasis 3 3 1 3 3 - - 2
Anorexia 3 0 2 3 3 2 2 2
Bulimia 2 0 2 2 3 2 2 2
Binge eating disorder 2 2 2 - 2 - - 2
Delusional disorder 2 1 3 2 1 - - 1
Impulse control Disorders IED** 2 0 1 - 1 2 2 1
Kleptomania 2 0 1 2 3 - - 1
Pathological gambling 2 0 1 1 3 1 1 1
Pyromania 2 0 - - - 2 2 -
Trichotillomania 2 0 2 1 3 - - 2
Paraphilias 2 0 2 -*** 1**** - - 2
NPSCDs***** 2 0 2 -*** 2 - - 1
Tourette's syndrome 3 0 2 3 2 2 2 1
Notes: *Obsessive-Compulsive disorder; **Intermittent explosive disorder; ***both paraphilias and [obviously] NPSCDs border on obsession-compulsion, see text for further details that associate these disorders with OCD (the data were not in at the time this table was published by McElroy et al.); ****an underestimate based on inadequate data available at the time, see text for details; *****Non-paraphilic sexual compulsion disorders. Scale: 0–3, 0 = no or minimal similarity, 3 = strong similarity, blank = insufficient data.

There is a molecular basis to the comorbidity in the above examples:

Some examples:

  • Body dysmorphic disorder, anorexia, trichotillomania, and onychophagia respond to drugs known as selective serotonin reuptake inhibitors (SSRIs).47 Speaking of serotonin, serotonin is involved in feeding, sexual behavior, and aggression across widely varying species.48, 49, 50 Serotonergic abnormalities are often found among paraphilias such as pedophilia,51, 52, 53 aggression and violent criminality in humans and non-human primates,54, 55, 56 and a variety of mental disorders including depression,57, 58, 59, 60 borderline personality disorder,61 bulimia, anorexia, panic attacks, and obsessive-compulsive disorder.62
  • Bulimia, binge eating disorder, kleptomania, intermittent explosive disorder, paraphilias, and non-paraphilic sexual compulsion disorders respond to a broad range of drugs such as antidepressants and mood stabilizing agents.63, 64 There exist reports of the remission of transsexualism, exhibitionism, fetishistic transvestism, and even homosexuality as a result of antidepressant use (see here). Antidepressant treatment that increases serotonin levels in the brain cures or diminishes paraphilias and non-paraphilic sexual compulsion disorders in several individuals.65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76 Depression is a common correlate of various disorders listed in Table 1 above. However, even non-depressed bulimics benefit from antidepressants.77
  • Urge-driven disorders such as pathological gambling disorder, alcoholism, borderline personality disorder with self-injurious behavior, cocaine abuse, mental retardation with self-injurious behavior, eating disorders, and sexual compulsion disorders have been successfully treated by opioid antagonists.78
  • The experience of pleasure and a sense of relief from stress correspond to the release of the neurotransmitter dopamine at several sites in the brain. Dopamine metabolism and dopamine-neurons are modified by serotonin-, opiod-, cannabinoid-, norepinephrine-, and GABA-neurons. Genetic or structural anomalies (including those resulting from developmental disturbances) involving such neurons or their relatedness can compromise adequate release of dopamine, prompting individuals to engage in behaviors that maintain appropriate dopamine levels in various brain regions. Examples of such behaviors include drug abuse (alcohol, cocaine, methamphetamine, heroin, nicotine, marijuana, and others), compulsive gambling, overeating, compulsive sexual behaviors, and risky behaviors. Specifically, inadequate levels of the dopamine D2 receptor increase the liability for multiple addictive, impulsive, and compulsive behaviors such as severe alcoholism or other drug dependence, binge eating of sugary foods, pathological gambling, compulsive sexual behaviors, ADHD, Tourette 's syndrome, autism, chronic violence, posttraumatic stress disorder, schizoid/avoidant cluster disorders, conduct disorder, and antisocial behavior.79, 80 A low level of dopamine D2 receptor binding in the left caudate nucleus has been reported in patients with obsessive-compulsive disorder.81

It should not be assumed that chemical imbalances alone are solely responsible for the problems described above because although some chemical imbalances are readily corrected by drugs, amelioration or remission of the associated disorders takes a long time.

When several mental disorders co-occur, someone may be prompted to argue that one or more mental disorders are specific manifestations of another mental disorder, but this is not always correct.82 For instance, some have argued that bulimia is a symptom of a mood disorder;83 however, a taxometric analysis revealed that bulimia is a disorder on its own.84

Let us address a system-level explanation of comorbidity. Depression is a common correlate of obsessive-compulsive disorder85 and the disorders listed in Table 1 above. Note that these disorders are characterized by a difficulty in maintaining stable brain functioning. Therefore, increased odds of depression in these disorders can be loosely understood in terms of resource depletion or exhaustion as a result of greater effort on the part of the brain to stabilize mental functioning. It should be obvious by now that nonheterosexuals find it more difficult to maintain stable mental functioning compared to heterosexuals, on average.


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