Schizophrenia risk in Afro-Caribbean Children, in UK

I just received a note in my “Guardian” newsfeed, regarding a much-lauded, best-selling book, entitled “Uprooting: From The Caribbean To The Countryside – Finding Home In An English Country Garden”, by Dr. Marchelle Farrell. [1]
According to the Guardian newspaper, Dr. Farrell, a psychiatrist of African/Trinidadian origin who studied, and is working, in the UK, describes the dismay and anxiety which she experienced, on hearing that as an Afro-Caribbean migrant, any children she might have were highly likely to develop schizophrenia.
She was advised that the risk of schizophrenia in the offspring of African/Caribbean-origin women, migrant to the UK, is “9 times higher” than that for indigenous British women.
She heard also that living in a city in the UK is “a critical factor, almost doubling the risk of psychotic illness in children”.

In response to this threatening, dreadful, stressful statistic, Dr. Farrell relocated to a small village in Somerset, England, where she and her family were made welcome. They are doing well.

Dr. Farrell explains that the problem of schizophrenia in the children of “black” West Indian women is modified by the social conditions of the particular area in which they settle: to quote her, “It seems that the risk factor for psychosis is not as simple as whether or not you live in a city. The more nuanced story seems to be about how much someone belongs, feels rooted in a place, and is accepted by the community in which they live”.

I have not as yet read “uprooting”: presently, it is not available in Canada. However the synopsis in the “Guardian” article instantly reminded me of the complications of stress-related intracellular hypothyroidism. [2a, 2b, 2c]
Thus my initial impression was that Dr. Farrell’s story is neither strange, nor surprising.
My thoughts were that schizophrenia in the offspring of immigrants is a predictable finding, which results from the socioeconomic status of the social group involved and that I would expect a similar finding among any group of city-dwelling immigrants, in any race-conscious society.

The description of Dr. Farrell’s situation however impelled me to expand on the subject, for the benefit of my readers and perhaps, as a caveat for my colleagues.
I therefore searched the web, for corroboration.

Immediately, I found an article titled “Schizophrenia in black Caribbeans living in the UK: an exploration of underlying causes of the high incidence rate” [3], by Rebecca Pinto, Mark Ashworth and Roger Jones, published by the British journal of general practice on 1 June, 2008. (DOI: 10.3399/bjgp08X29925), PMCID: PMC2418996, PMID: 18505621.
There are of course other articles, but this one, by Pinto et al. is sufficiently clear, detailed and logical that further citations are unnecessary for the purposes of this opinion piece.

Reporting on a review of 604 articles written between 1987 and 2007, of which 231 were relevant to the subject, the authors verified that the lifetime risk of developing schizophrenia in siblings of second-generation (UK-born) African-Caribbeans is 17%.
In first-generation African-Caribbeans it is 9%, and in white British, it is just 2%.
However, they noted that studies conducted in the 1990s in Jamaica, Trinidad, and Barbados all report similar schizophrenia incidence rates to those found in the native UK population, a fact which definitively excludes genetic causes of schizophrenia in the study populations.

Based on these reports, it appears that high rates of schizophrenia among black Caribbeans are a feature of the emigrated, rather than the original, community, and for further emphasis, high rates of schizophrenia had previously been reported in the children of Norwegians emigrating to the United States.

Here is the logic:

(A) Healthy humans, with normally functioning thyroid glands, are naturally equipped to withstand stress; but those suffering from reduced thyroid function (hypothyroidism), whether autoimmune, post infective or stress-related, have been reported to produce children with some selection or combination of autism, schizophrenia, ADD, ADHD, gender dysphoria and major depressive disorder, in higher than usual numbers.
(B) The major output from the thyroid gland, thyroxine (T4), is inactive. It is converted into T3 (triiodothyronine) in the peripheral cells of the body. The T3 in human blood is all produced in peripheral cells.
(C) Under high-stress conditions, Cortisol is released in increased quantity by the adrenal glands.
Cortisol causes abnormal conversion of T4 into inactive “reverse T3” (rT3), instead of active T3.
Further, it erases normal T3 from all cells in the body, excepting those within the pituitary gland.
(D) Thus the stress response results in “T3 starvation”, better termed “Intracellular Hypothyroidism”, inside the cells. [3]
In this situation no T3 is made and none enters the blood. The serum T3 level is catastrophically low and the level of rT3 rises.
This amounts to deep hypothyroidism, which more often than not prevents conception, or causes spontaneous abortion of a pregnancy, as one of its many complications.

Caveat: the amount of rT3 is of no consequence, but its level indicates the degree to which T3 formation is being suppressed and the ratio between T3 and rT3 diagnoses, or excludes, IH (normally, T3/rT3 is greater than 20.0 aso thend any number less than 20 diagnoses IH.

The scenario:
The Afro-Caribbean woman, although subject to racial profiling and economic insecurity, accepts, controls and ignores her stress.
She has borderline-low serum T3 levels due to mild, stress-related, elevated cortisol in her blood. Her blood T3 is just high enough to allow conception and pregnancy, but she appears completely normal, though perhaps unusually fatigued.
She enters into a relationship and begins a pregnancy in the usual fashion, but in 17% of cases, the added anxiety of pregnancy results in even higher cortisol production by the 5th or 6th week after conception,
In those 17% of Afro-Caribbean women, suppression of T3 production is so severe that Intracellular Hypothyroidism ensues, with frankly low blood T3 levels, as outlined in (D).
As a result the developing fetus gets little, or no T3 and suffers “T3 starvation”, which is not relieved until its own thyroid begins to produce thyroxine, about 16 weeks after conception.

The problem:
The baby’s brain begins to develop in the 3rd week of pregnancy and very important “wiring” connections are made between the 8th and the 14th weeks.
If the mother is hypothyroid, this delicate, all-important process takes place in a hypothyroid fetus and subtle abnormalities of “brain wiring” result, manifesting a variable degree of eccentricity of cognitive function.

The diagnosis:
T3 starvation”, a.k.a. “low T3 syndrome”, “functional hypothyroidism”, “nonthyroidal illness”, “euthyroid sick syndrome” etc., is more descriptively termed “Intracellular Hypothyroidism” (IH),
IH is easily diagnosed by dividing the blood T3 level by the rT3 level: IH is present if the ratio is <20.
However doctors are advised not to check T3 and rT3 levels and therefore, the diagnosis is missed.

Ideally, stress relief would prevent IH, but that is hardly possible with stress of socioeconomic origin.
However assessment of the T3/rT3 ratio before conception, or immediately upon diagnosis of pregnancy, and repeated 6 weeks post-conception,would provide early diagnosis.
Early diagnosis would permit correction of the mother’s IH, thus providing the growing baby with an adequate supply of thyroid 3 hormone during the crucial first and second trimesters of pregnancy, ensuring unimpeded “brain wiring” and reducing the baby’s liability to imperfect cognition, ADD, gender dysphoria, schizophrenia etc.

Ongoing management:
From the baby’s point of view, support of the mother’s thyroid function could be discontinued after 16 weeks of pregnancy, when the fetus begins to produce its own thyroid hormone.
However the mother will fare better, with less weight gain and less chance of postpartum depression, if her thyroid hormone levels are rechecked periodically and supported as necessary by prescription of (slow-release) T3.


[1] Uprooting: From the Caribbean to the Countryside – Finding Home in an English Country Garden, by Marchelle Farrell, https://www.goodreads.com/book/show/157204135-uprooting

[2a] IH (intracellular hypothyroidism): by Gervais A. Harry, published by Research Gate, May 2023, https://www.researchgate.net/publication/370772568_INTRACELLULAR_HYPOTHYROIDISM

[2b) Stress Causes Hypothyroidism: why, vs. how!, by Gervais A. Harry, cbhrt.ca, December 14, 2022.


[3] Pinto R, Ashworth M, Jones R. Schizophrenia in black Caribbeans living in the UK: an exploration of underlying causes of the high incidence rate. Br J Gen Pract. 2008 Jun;58(551):429-34.
doi: 10.3399/bjgp08X299254. PMID: 18505621; PMCID: PMC2418996.

I am a Toronto-trained Urologist. I practiced in downtown Toronto, from 1977 to 1997, when I went to Saudi Arabia as chief of Urology at the Armed Forces (teaching) hospital in Tabuk. Returning to Toronto in Y2000, I switched to family practice. In 2007, began to prescribe Hormone Restoration Therapy and in 2012, I became a member of the American Academy of Antiaging Medicine [A4M]. I successfully wrote the A4M's written examination in December, 2013 and In May, 2016 I passed the oral examination, for accreditation as a BHRT consultant. In 2014 I began BHRT practice in Collingwood, Ontario and in January, 2017, joined the Stone Tree Naturopathic Clinic. Now I am 82 and have retired, but it seems wasteful to jettison my learning and experience: the medical establishment knows nothing of BHRT / Functonal medicine and I feel obliged to offer my knowledge in the interest of those who are willing to think outside the box. MY QUALIFICATIONS: MB, BS, (from UWI), 1964. LMCC 1969. FRCSC (Urology), 1974. ECFMG 1984. Florida license 1998 [inactive], ABAARM Certification [A4M], 2016. I am a Member of CSAMM [the Canadian Society for Aging and Metabolic Medicine], the OMA&CMA, SUSO, CUA, RCP&S/C. PRACTICE TO DATE: Consultation in Functional Medicine, including assessment of Chronic Fatigue Syndrome, Fibromyalgia, Andropause, Menopause, Teenage and Postpartum Depression/Panic Attacks, Thyroid Hormone malfunction, Infertility, Sexual Dysfunction and “the Undiagnosable”. ALL ARE WELCOME to read, comment or question!