All subjects · Psychology · WPS04 Clinical Psychology and Psychological Skills

Contemporary study: Suzuki et al. (2014) underweight in Japanese inpatients with schizophrenia

Edexcel IAL Psychology · WPS04 Clinical Psychology and Psychological Skills

Suzuki et al. (2014) is the compulsory contemporary study for schizophrenia (8.2.2). It challenges the Western assumption that people with schizophrenia are mainly at risk of weight gain, showing how features can differ by culture.

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Aims and sample

Aims: to find the prevalence of underweight and overweight or obesity, and nutritional status, in Japanese inpatients with schizophrenia.

Sample: 333 inpatients with schizophrenia (DSM-IV-TR), aged 16 to 80, from 9 psychiatric hospitals in Niigata Prefecture, Japan, and 191 healthy controls matched for age and sex. Patients with overt physical illness, recent drug changes or other drugs (except benzodiazepines and mood stabilisers) were excluded. All gave written informed consent.

Procedure

Height and weight measured and BMI calculated: underweight under 18.5, standard 18.5 to under 25, overweight or obese over 25.
Fasting blood samples (fast of more than 9 hours) measured nutritional markers: total protein, total cholesterol, triglycerides and fasting glucose.
Undernutrition was operationalised as values below cut-offs, for example hypoproteinaemia (total protein under 6.7 g/dL).
Design: a cross-sectional comparison of patients and controls (a correlational / quasi-experimental design).

Results

Measure	Patients	Controls
Underweight (BMI under 18.5)	14.1%	4.2%
Standard weight	59.2%	73.8%
Overweight or obese	26.7%	22.0%
Hypoproteinaemia	22.3%	2.1%
Hypocholesterolaemia	14.7%	1.6%

Conclusions and evaluation

Conclusions: patients' nutritional status was poorer than controls'. Underweight was more common than in the general Japanese population, while overweight did not differ from controls. Underweight patients were mainly taking aripiprazole and others mainly olanzapine. Poor nutrition (for example low protein and cholesterol) was common, so physical health and nutrition should be monitored in inpatients.

Evaluation

Objective physical measures (BMI, blood tests): reliable and hard to bias.
Large sample from 9 hospitals, with matched controls.
Correlational: cannot show that schizophrenia or medication causes underweight; drug type is a confounding variable.
Generalisability: Japanese inpatients only, with exclusions, so may not apply to outpatients or other cultures; but that is also its value, showing cultural differences in features (8.1.3).
Application: supports monitoring nutrition in inpatient care.

Worked example

Approximate counts reconstructed from the percentages are 47 of 333 patients and 8 of 191 controls underweight. Carry out a chi-squared test (2 x 2) and decide whether the difference is significant at p ≤ .05 (two-tailed).

Observed: patients 47 underweight, 286 not; controls 8 underweight, 183 not.
Expected for each cell = row total x column total / grand total: 34.95, 298.05, 20.05, 170.95.
Chi-squared = sum of (O - E)² / E = 12.73, df = (2 - 1)(2 - 1) = 1.
Critical value (df 1, two-tailed p ≤ .05) = 3.84. 12.73 ≥ 3.84, so significant.

Answer: Chi-squared = 12.73, df = 1: significant at p ≤ .05; underweight was more common in patients.

Key idea: Suzuki et al. (2014): 333 Japanese inpatients with schizophrenia vs 191 matched controls; BMI and fasting blood tests. Underweight 14.1% vs 4.2%; hypoproteinaemia 22.3% vs 2.1%. Objective measures, but correlational and culture-specific.

Check yourself

Underweight was 14.1% in patients and 4.2% in controls. How many times more common was it in patients? Give your answer to 2 decimal places.
Show answer
3.36. 14.1 / 4.2 = 3.36.
About how many of the 333 patients were underweight (14.1%)? Give a whole number.
Show answer
47 patients. 333 x 0.141 = 46.95, about 47.
Using the counts in the worked example, calculate chi-squared to 2 decimal places.
Show answer
12.73. Chi-squared = 12.73.
How was underweight operationalised in Suzuki et al. (2014)?
- A BMI under 18.5
- Self-reported feelings of thinness
- Weight under 40 kg
- A doctor's impression
Show answer
A BMI under 18.5. BMI was calculated from measured height and weight.
What was the control group in Suzuki et al. (2014)?
- Patients with depression
- Patients in America
- 191 healthy volunteers matched for age and sex
- No control group was used
Show answer
191 healthy volunteers matched for age and sex. Matched healthy controls.
Which is a confounding variable in Suzuki et al. (2014)?
- The type of antipsychotic medication patients were taking
- The height of the researchers
- The number of hospitals
- The time of the blood test after a 9-hour fast
Show answer
The type of antipsychotic medication patients were taking. Drug type differed between weight groups and could cause weight differences.
Explain how Suzuki et al. (2014) relates to cultural issues in diagnosis and features of schizophrenia.
Show answer
It found that Japanese inpatients were often underweight, unlike the Western focus on weight gain, suggesting the features of schizophrenia and its treatment can differ between cultures.. Features such as weight differ across cultures.

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Last updated 8 November 2026. Spotted a mistake? Tell us.