The two leading global causes of death are cardiovascular disease and cancer , both of which are associated to some extent with inflammation and oxidative stress . Consequently , it is easy to understand the rationale for supplement use among consumers , as many compounds have a purported anti-inflammatory or antioxidant action and which provides justification for their use .
In light of the current levels of supplement use , the US Preventative Services Task Force ( USPSTF ) has recently updated its recommendations from 2014 after a review of the evidence on the efficacy of supplements with single nutrients or multivitamins for a reduction in the risk of cardiovascular disease or cancer . 4 However , the USPSTF review of the available evidence offers little support for the use of supplements and even identifies possible harm with some compounds .
Perhaps the most disturbing finding from the report is that the USPSTF concluded that there is moderate certainty evidence that the use of beta carotene is associated with more harm than benefit . In fact , an analysis of 5 studies found an increased risk of cardiovascular disease mortality , after 4 to 12 years , among those supplementing with beta carotene ( odds ratio , OR = 1.10 , 95 % CI 1.02 – 1.19 ). Additionally , there was no association between use of vitamin A and all-cause mortality ( OR = 1.16 , 95 % CI 0.80 – 1.69 ) and the combination of vitamin A and beta carotene led to a significantly increased risk of lung cancer among individuals who either smoked or were exposed to asbestos . A similar lack of benefit for all-cause mortality was found for vitamins B3 and B6 , C , D or E , folic acid with or without vitamin B12 or selenium .
With regard to multivitamin supplements , there was also no detectable mortality benefit ( OR = 0.94 , 95 % CI 0.87 – 1.01 ). Moreover , when analysed separately for cardiovascular disease and cancer , there were no overall benefits .
Fortunately , apart from the abovementioned harms from beta carotene , the USPSTF could find no evidence to suggest any harm from the use of any of the other supplements examined . The authors concluded that , to date , there was no evidence to assess the benefits and harms of supplements for the prevention of cardiovascular disease or cancer .
References 1 Kantor ED et al . Trends in Dietary Supplement Use Among US Adults From 1999 – 2012 . JAMA 2016 ; 316 ( 14 ): 1464 – 1474 . 2 Skeie G et al . Use of dietary supplements in the European Prospective Investigation into Cancer and Nutrition calibration study . Eur J Clin Nutr 2009 ; Suppl4 : S226 – 38 . 3 Dickinson A et al . Consumer usage and reasons for using dietary supplements : report of a series of surveys . J Am Coll Nutr 2014 ; 33 ( 2 ): 176 – 82 . 4 US Preventative Services Task Force . Vitamin , Mineral ,
and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer : US Preventive Services Task Force Recommendation Statement . JAMA 2022 ; 327 ( 23 ): 2326 – 33 .
Negative symptoms in schizophrenia improved by non-invasive brain stimulation
Patients with schizophrenia experience both positive and negative symptoms . Positive symptoms reflect an excess or distortion of normal function ( for example , delusions , hallucinations , disorganised behaviour ), whereas negative symptoms refer to a diminution or absence of normal behaviours related to motivation and interest . 1 Prominent negative symptoms affect approximately 40 % of patients and while anti-psychotic medication leads to a significant improvement in positive symptoms , the drugs have much less impact on negative symptoms . Furthermore , these negative symptoms substantially contribute to the overall disease burden and there are no approved treatments specifically directed toward the management of negative symptoms . 2
There is some evidence that non-invasive brain stimulation ( NIBS ) techniques , such as transcranial magnetic stimulation , exert positive effects on the brain , and a 2019 meta-analysis 3 concluded that transcranial direct current stimulation could be a promising treatment for auditory hallucinations ; that is , the positive symptoms of schizophrenia . Nevertheless , although NIBS has been used to treat negative symptoms in schizophrenia , the available evidence is conflicting , with one study reporting beneficial effects 4 and another , that deep transcranial magnetic stimulation had no effect on either positive or negative symptoms . 5
For this study , 6 the authors undertook a systematic review and network meta-analysis to evaluate the comparative efficacy of different NIBS techniques for the management of the negative symptoms in schizophrenia . They searched for randomised trials that compared NIBS to sham treatment , in patients with schizophrenia and for the management of negative symptoms . The researchers used a co-primary outcome which was a change in the severity of negative symptoms and acceptability of the intervention , which was accessed in terms of the dropout rates .
A total of 48 trials involving 2211 participants with a mean age of 38.7 years ( 30.6 % female ) were included in their analysis . The mean duration of treatment in the trials was 2.8 weeks and the mean duration of follow-up ( including treatment ) was 9 weeks . In addition to NIBS , all trials permitted the
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